Maths

In drilling world’s deepest hole it was found that the temperature T in degree Celsius, x km below the earth’s surface was given by T = 30 + 25 (x – 3), 3 ≤ x ≤ 15. At what depth will the temperature be between 155°C and 205°C?

\[T\text{ }=\text{ }30\text{ }+\text{ }25\left( x\text{ }\text{ }3 \right),\text{ }3\text{ }\le \text{ }x\text{ }\le \text{ }15;\] where, T = temperature and x = depth inside the earth The...

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A solution of 9% acid is to be diluted by adding 3% acid solution to it. The resulting mixture is to be more than 5% but less than 7% acid. If there is 460 litres of the 9% solution, how many litres of 3% solution will have to be added?

According to the question, Let x litres of 3% solution is to be added to 460 liters of the 9% of solution Then, we get, Total solution = \[\left( 460\text{ }+\text{ }x \right)\text{ }litres\] Total...

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The water acidity in a pool is considered normal when the average pH reading of three daily measurements is between 8.2 and 8.5. If the first two pH readings are 8.48 and 8.35, find the range of pH value for the third reading that will result in the acidity level being normal.

According to the question, First reading = 8.48 Second reading = 8.35 Now, let the third reading be ‘x’ Average pH should be between 8.2 and 8.5 Average \[pH~=\text{ }\left( 8.48\text{ }+\text{...

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On a square cardboard sheet of area

    \[784\]

    \[c{{m}^{2}}\]

, four congruent circular plates of maximum size are placed such that each circular plate touches the other two plates and each side of the square sheet is tangent to two circular plates. Find the area of the square sheet not covered by the circular plates.

Given Area of the square = \[784\] \[c{{m}^{2}}\] Hence Side of the square = \[\sqrt{Area}\] = \[\sqrt{784}\] = \[28\] cm Given that the four circular plates are congruent, Therefore diameter of...

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In Fig. 11.17, ABCD is a trapezium with AB || DC, AB =

    \[18\]

cm, DC =

    \[32\]

cm and distance between AB and DC =

    \[14\]

cm. If arcs of equal radii

    \[7\]

cm with centres A, B, C and D have been drawn, then find the area of the shaded region of the figure.

Solution Given AB = \[18\] cm, DC = \[32\] cm Given, Distance between AB and DC = Height = \[14\] cm We know that  Area of the trapezium = (\[1/2\]) × (Sum of parallel sides) × Height =...

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Sides of a triangular field are

    \[15\]

m,

    \[16\]

m and

    \[17\]

m. With the three corners of the field a cow, a buffalo and a horse are tied separately with ropes of length

    \[7\]

m each to graze in the field. Find the area of the field which cannot be grazed by the three animals.

Solution From the given question, We got Sides of the triangle are \[15\] m, \[16\] m and \[17\] m. Then, perimeter of the triangle = \[(15+16+17)\] m = \[48\]m Therefore, Semi-perimeter of the...

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If the circumference of a circle and the perimeter of a square are equal, then (A) Area of the circle = Area of the square (B) Area of the circle > Area of the square (C) Area of the circle < Area of the square (D) Nothing definite can be said about the relation between the areas of the circle & square.

The correction option is (B) Area of the circle > Area of the square Explanation: From  the given question, Circumference of a circle of radius r  = Perimeter of a square of side a Let us take  r...

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If the sum of the circumferences of two circles with radii

    \[R1\]

and

    \[R2\]

is equal to the circumference of a circle of radius

    \[R\]

, then (A)

    \[{{R}_{1}}+{{R}_{2}}=R\]

(B)

    \[{{R}_{1}}+{{R}_{2}}>R\]

(C)

    \[{{R}_{1}}+{{R}_{2}}<R\]

(D) Nothing definite can be said about the relation among

    \[{{R}_{1}}\]

,

    \[{{R}_{2}}\]

&

    \[R\]

.

The Correct option(A) \[{{R}_{1}}+{{R}_{2}}=R\] Explanation: From the given question, We got sum of the circumferences of two circles with radii \[R1\] and \[R2\] is equal to the circumference of a...

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To construct a triangle similar to a given △ABC with its sides 7/3 of the corresponding sides of △ABC, draw a ray BX making acute angle with BC and X lies on the opposite side of A with respect to BC. The points B1, B2, …., B7 are located at equal distances on BX, B3 is joined to C and then a line segment B6C‘ is drawn parallel to B3C where C‘ lies on BC produced. Finally, line segment A‘C‘ is drawn parallel to AC.

False Support: Allow us to attempt to build the figure as given in the inquiry. Steps of development, Define a boundary section \[BC.\] With \[B\text{ }and\text{ }C\]as focuses, draw two circular...

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Draw a parallelogram

    \[\mathbf{ABCD}\]

in which

    \[\mathbf{BC}\text{ }=\text{ }\mathbf{5}\text{ }\mathbf{cm},\text{ }\mathbf{AB}\text{ }=\text{ }\mathbf{3}\text{ }\mathbf{cm}\]

and angle

    \[\mathbf{ABC}\text{ }=\text{ }\mathbf{60}{}^\circ ,\]

divide it into triangles

    \[\mathbf{BCD}\]

and

    \[\mathbf{ABD}\]

by the diagonal

    \[\mathbf{BD}.\]

Construct the triangle

    \[\mathbf{BD}~\mathbf{C}~\]

similar to triangle

    \[\mathbf{BDC}\]

with scale factor

    \[\mathbf{4}/\mathbf{3}\]

. Draw the line segment

    \[\mathbf{D}\mathbf{A}~\]

parallel to

    \[\mathbf{DA}\]

where

    \[\mathbf{A}\]

lies on extended side

    \[\mathbf{BA}\]

. Is

    \[\mathbf{A}\mathbf{BC}\mathbf{D}\]

a parallelogram?

Steps of construction:   Define a boundary \[\mathbf{AB}=\mathbf{3}\text{ }\mathbf{cm}.\] Draw a beam \[\mathbf{BY}\]making an intense \[\angle \mathbf{ABY}=\mathbf{60}{}^\circ .\] With focus...

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To divide a line segment

    \[\mathbf{AB}\]

in the ratio

    \[\mathbf{5}\text{ }:\text{ }\mathbf{6}\]

, draw a ray

    \[\mathbf{AX}\]

such that

    \[\angle \mathbf{BAX}\]

is an acute angle, then draw a ray

    \[\mathbf{BY}\]

parallel to

    \[\mathbf{AX}\]

and the points

    \[{{\mathbf{A}}_{\mathbf{1}}},\text{ }{{\mathbf{A}}_{\mathbf{2}}},\text{ }{{\mathbf{A}}_{\mathbf{3}}},\text{ }\ldots \]

and

    \[{{\mathbf{B}}_{\mathbf{1}}},\text{ }{{\mathbf{B}}_{\mathbf{2}}},\text{ }{{\mathbf{B}}_{\mathbf{3}}},\text{ }\ldots \]

are located at equal distances on ray

    \[\mathbf{AX}\]

and

    \[\mathbf{BY}\]

, respectively. Then the points joined are

    \[\left( \mathbf{A} \right)\text{ }{{\mathbf{A}}_{\mathbf{5}}}~\mathbf{and}\text{ }{{\mathbf{B}}_{\mathbf{6}}}~\]

    \[\left( \mathbf{B} \right)\text{ }{{\mathbf{A}}_{\mathbf{6}}}~\mathbf{and}\text{ }{{\mathbf{B}}_{\mathbf{5}}}~\]

    \[~\left( \mathbf{C} \right)\text{ }{{\mathbf{A}}_{\mathbf{4}}}~\mathbf{and}\text{ }{{\mathbf{B}}_{\mathbf{5}}}\]

    \[\left( \mathbf{D} \right)\text{ }{{\mathbf{A}}_{\mathbf{5}}}~\mathbf{and}\text{ }{{\mathbf{B}}_{\mathbf{4}}}\]

\[\left( \mathbf{A} \right)\text{ }{{\mathbf{A}}_{\mathbf{5}}}~\mathbf{and}\text{ }{{\mathbf{B}}_{\mathbf{6}}}\] As per the inquiry, A line portion \[AB\]in the proportion \[5:7\] Along these...

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To divide a line segment

    \[\mathbf{AB}\]

in the ratio

    \[\mathbf{5}:\mathbf{7}\]

, first a ray

    \[\mathbf{AX}\]

is drawn so that

    \[\mathbf{BAX}\]

is an acute angle and then at equal distances points are marked on the ray

    \[\mathbf{AX}\]

such that the minimum number of these points is (A)

    \[\mathbf{8}\]

(B)

    \[\mathbf{10}\]

(C)

    \[~\mathbf{11}\]

(D)

    \[\mathbf{12}\]

SOLUTION:- \[\left( D \right)\text{ }12\] As indicated by the inquiry, A line fragment \[AB\]in the proportion \[5:7\] In this way, \[A:B\text{ }=\text{ }5:7\] Presently, Draw a beam \[AX\]making an...

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Two APs have the same common difference. The first term of one AP is 2 and that of the other is 7 The difference between their 10th terms is the same as the difference between their 21st terms, which is the same as the difference between any two corresponding terms. Why?

Solution: Consider two APs with the first terms as ‘a’ and ‘A’. The common differences are ‘d’ and ‘D’, respectively. Assume that n is any term. ${{a}_{n}}~=a+\left( n-1 \right)d$ ${{A}_{n}}~=\text{...

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Choose the correct answer from the given four options in the following questions: The first four terms of an AP, whose first term is –2 and the common difference is –2, are
(A) – 2, 0, 2, 4 (B) – 2, 4, – 8, 16 (C) – 2, – 4, – 6, – 8 (D) – 2, – 4, – 8, –16

Solution: Option (C) – 2, – 4, – 6, – 8 is the correct answer. Explanation: First term, a = – 2 Second Term, d = – 2 ${{a}_{1\text{ }}}=~a=\text{ -}2$ It is known that the AP’s nth term is...

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Choose the correct answer from the given four options in the following questions: The list of numbers – 10, – 6, – 2, 2,… is (A) an AP with d = – 16 (B) an AP with d = 4 (C) an AP with d = – 4 (D) not an AP

Solution: Option (B) an AP with d = 4 is the correct answer. Explanation: According to the question, ${{a}_{1\text{ }}}=~\text{ }-10$ ${{a}_{2\text{ }}}=\text{ }-6$ ${{a}_{3\text{ }}}=~\text{ }-2$...

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The points A (x1, y1), B (x2, y2) and C (x3 y3) are the vertices of ABC.
(i) Find the coordinates of points Q and R on medians BE and CF, respectively such that BQ : QE = 2 : 1 and CR : RF = 2 : 1
(ii) What are the coordinates of the centroid of the triangle ABC?

Solution: (i) Let (p, q) be the coordinates of a point Q. Provided, The point Q (p, q), Divide the line joining $\mathrm{B}\left(\mathrm{x}{2}, \mathrm{y}{2}\right)$ and...

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The points A (x1, y1), B (x2, y2) and C (x3 y3) are the vertices of ABC. (i) The median from A meets BC at D. Find the coordinates of the point D. (ii) Find the coordinates of the point P on AD such that AP : PD = 2 : 1

Solution: According to the given question, A, B and C are the vertices of ΔABC A(x1, y1), B(x2, y2), C(x3, y3) are the coordinates of A, B and C. (i) According to the information provided, D is BC's...

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State whether the following statements are true or false. Justify your answer. Point P (0, 2) is the point of intersection of y–axis and perpendicular bisector of line segment joining the points A (–1, 1) and B (3, 3).

Solution: The statement given in the question is false. Justification: We know that the points on the perpendicular bisector of the line segment joining two points are equidistant from the two...

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Form the pair of linear equations for the following problems and find their solution by substitution method.(i) The difference between two numbers is 26 and one number is three times the other. Find them.(ii) The larger of two supplementary angles exceeds the smaller by 18 degrees. Find them.

Arrangement (i): Leave the two numbers alone x and y individually, to such an extent that y > x. As indicated by the inquiry, \[y\text{ }=\text{ }3x\text{ }\ldots \text{ }\ldots \text{ }\ldots...

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Choose the correct answer from the given four options in the following questions: AOBC is a rectangle whose three vertices are vertices A (0, 3), O (0, 0) and B (5, 0). The length of its diagonal is (A) 5 (B) 3 (C) √34 (D) 4

Solution: Option (C) √34 is the correct answer. The three vertices are: $A\text{ }=\text{ }\left( 0,\text{ }3 \right)$, $O\text{ }=\text{ }\left( 0,\text{ }0 \right)$ , $B\text{ }=\text{ }\left(...

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For going to a city B from city A, there is a route via city C such that AC⊥CB, AC = 2 x km and CB = 2 (x + 7) km. It is proposed to construct a 26 km highway which directly connects the two cities A and B. Find how much distance will be saved in reaching city B from city A after the construction of the highway.

Solution: According to the given question, AC⊥CB, $AC\text{ }=\text{ }2x\text{ }km$, $CB=2\left( x+7 \right)km$ and $AB=26\text{ }km$ As a result, we get triangle ACB right angled at C. Now, using...

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A 5 m long ladder is placed leaning towards a vertical wall such that it reaches the wall at a point 4 m high. If the foot of the ladder is moved 1.6 m towards the wall, then find the distance by which the top of the ladder would slide upwards on the wall.

Solution: Let 5 m be the length of the ladder AC. Let 4m be the height of the wall on which ladder is placed is BC From right angled triangle EBD, Now using the Pythagoras Theorem,...

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The monthly income of 100 families are given as below : Income (in Rs) Number of families 0-5000 8 5000-10000 26 10000-15000 41 15000-20000 16 20000-25000 3 25000-30000 3 30000-35000 2 35000-40000 1 Calculate the modal income.

  As per the information given, The most elevated recurrence = 41, 41 lies in the stretch 10000 – 15000. Here, l = 10000, fm = 41,f1 = 26,f2 = 16 and h = 5000 \[=\text{ }10000\text{ }+\text{...

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The maximum bowling speeds, in km per hour, of 33 players at a cricket coaching centre are given as follows: Speed (km/h) 85-100 100-115 115-130 130-145 Number of players 11 9 8 5 Calculate the median bowling speed.

First we develop the combined recurrence table Speed ( in km/h)               Number of players           Cumulative recurrence 85 – 100              11           11 100 – 115           ...

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Weekly income of 600 families is tabulated below : Weekly income Number of families (in Rs) 0-1000 250 1000-2000 190 2000-3000 100 3000-4000 40 4000-5000 15 5000-6000 5 Total 600 Compute the median income.

Week by week Income   Number of families (fi)   Cumulative recurrence (cf) 0-1000  250        250 1000-2000           190        250 + 190 = 400 2000-3000           100        440 + 100 = 540...

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Given below is a cumulative frequency distribution showing the marks secured by 50 students of a class: Marks Below 20 Below 40 Below 60 Below 80 Below 100 Number of students 17 22 29 37 50 Form the frequency distribution table for the data.

The recurrence circulation table for given information. Marks    Number of understudies 0 – 20    12 20 – 40  22 – 17 = 5 40 – 60  29 – 22 = 7 60 – 80  37 – 29 = 8 80 – 100              50 – 37 =...

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The following are the ages of 300 patients getting medical treatment in a hospital on a particular day: Age (in years) 10-20 20-30 30-40 40-50 50-60 60-70 Number of patients 60 42 55 70 53 20 Form: ALess than type cumulative frequency distribution. More than type cumulative frequency distribution

  (I) Less than type Age (in year)       Number of patients Under 10             0 Under 20             60 + 0 = 60 Under 30             60 + 42 = 102 Under 40             102 + 55 = 157 Under...

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Find the unknown entries a, b, c, d, e, f in the following distribution of heights of students in a class: Height Frequency Cumulative frequency (in cm) 150-155 12 a 155-160 b 25 160-165 10 c 165-170 d 43 170-175 e 48 175-180 2 f Total 50

  Tallness (in cm)  Frequency           Cumulative recurrence given       Cumulative recurrence 150 – 155            12           a             12 155 – 160            b            ...

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Form the frequency distribution table from the following data : Marks (out of 90) Number of candidates More than or equal to 80 4 More than or equal to 70 6 More than or equal to 60 11 More than or equal to 50 17 More than or equal to 40 23 More than or equal to 30 27 More than or equal to 20 30 More than or equal to 10 32 More than or equal to 0 34

The recurrence dissemination table for the given information is: Class Interval      Number of understudies 0-10       34 – 32 = 2 10-20     32 – 30 = 2 20-30     30 – 27 = 3 30-40     27 – 23 = 4...

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The following table shows the cumulative frequency distribution of marks of 800 students in an examination: Marks Number of students Below 10 10 Below 20 50 Below 30 130 Below 40 270 Below 50 440 Below 60 570 Below 70 670 Below 80 740 Below 90 780 Below 100 800 Construct a frequency distribution table for the data above.

The recurrence circulation table for the given information is: Class Interval      Number of understudies 0-10       10 10-20     50 – 10 = 40 20-30     130 – 50 = 80 30-40     270 – 130 = 140...

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The following is the distribution of weights (in kg) of 40 persons : Weight (in kg) 40-45 45-50 50-55 55-60 60-65 65-70 70-75 75-80 Number of persons 4 4 13 5 6 5 2 1 Construct a cumulative frequency distribution (of the less than type) table for the data above.

Weight (in kg)    Cumulative recurrence Under 45             4 Under 50             4 + 4 = 8 Under 55             8 + 13 = 21 Under 60             21 + 5 = 26 Under 65             26 + 6 = 32 Under...

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The mileage (km per litre) of 50 cars of the same model was tested by a manufacturer and details are tabulated as given below : Mileage (km/l) 10-12 12-14 14-16 16-18 Number of cars 7 12 18 13 Find the mean mileage. The manufacturer claimed that the mileage of the model was 16 km/litre. Do you agree with this claim?

Mileage (km L-1)              Class – Marks (xi)             Number of vehicles (fi)   fixi 10 – 12  11           7             77 12 – 14  13           12           156 14 – 16  15          ...

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The weights (in kg) of 50 wrestlers are recorded in the following table : Weight (in kg) 100-110 110-120 120-130 130-140 140-150 Number of wrestlers 4 14 21 8 3 Find the mean weight of the wrestlers.

Weight (in kg)    Number of Wrestlers (fi)               Class Marks (xi)  Deviation (di = xi – a) fidi 100 – 110            4             105        –20        –80 110 – 120            14          ...

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An aircraft has 120 passenger seats. The number of seats occupied during 100 flights is given in the following table : Number of seats 100-104 104-108 108-112 112-116 116-120 Frequency 15 20 32 18 15 Determine the mean number of seats occupied over the flights.

  Class Interval      Class Marks (xi)  Frequency (fi)     Deviation (di = xi – a)      fidi 100 – 104            102        15           –8           –120 104 – 108            106       ...

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The daily income of a sample of 50 employees are tabulated as follows : Income (in Rs) 1-200 201-400 401-600 601-800 Number of employees 14 15 14 7 Find the mean daily income of employees.

C.I          xi            di = (xi – a)          Fi            fidi 1 – 200  100.5     –200      14           –2800 201 – 400            300.5     0             15           0 401 – 600           ...

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The following tabe gives the number of pages written by Sarika for completing her own book for 30 days : Number of pages written per day 16-18 19-21 22-24 25-27 28-30 Number of days 1 3 4 9 13 Find the mean number of pages written per day.

Class Marks         Mid – Value (xi) Number of days (fi)         fixi 15.5 – 18.5          17           1             17 18.5 – 21.5          20           3             60 21.5 – 24.5         ...

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In calculating the mean of grouped data, grouped in classes of equal width, we may use the formula where a is the assumed mean. a must be one of the mid-points of the classes. Is the last statement correct? Justify your answer.

No, the assertion isn't right. It isn't required that expected mean ought to be the mid – mark of the class span. a can be considered as any worth which is not difficult to work on it.

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Apoorv throws two dice once and computes the product of the numbers appearing on the dice. Peehu throws one die and squares the number that appears on it. Who has the better chance of getting the number 36? Why?

Apoorv toss two dice on the double. Thus, the all out number of results = 36 Number of results for getting item 36 = 1(6×6) ∴ Probability for Apoorv = 1/36 Peehu tosses one kick the bucket, Thus,...

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Consider the following distribution : Marks obtained Number of students More than or equal to 0 63 More than or equal to 10 58 More than or equal to 20 55 More than or equal to 30 51 More than or equal to 40 48 More than or equal to 50 42 The frequency of the class 30-40 is (A) 3 (B) 4 (C) 48 (D) 51

(A) 3 Clarification: Imprints Obtained            Number of students        Cumulative Frequency 0-10       (63 – 58) = 5       5   10-20     (58 – 55) = 3       3   20-30     (55 – 51) =...

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The times, in seconds, taken by 150 athletes to run a 110 m hurdle race are tabulated below Class 13.8-14 14-14.2 14.2-14.4 14.4-14.6 14.6-14.8 14.8-15 Frequency 2 4 5 71 48 20 The number of athletes who completed the race in less than 14.6 seconds is : A11 (B) 71 (C) 82 (D) 130

(C) 82 Clarification: The quantity of competitors who finished the race in under 14.6 second= 2 + 4 + 5 + 71 = 82 Subsequently, choice (C) is right

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Consider the data : Class 65-85 85-105 105-125 125-145 145-165 165-185 185-205 Frequency 4 5 13 20 14 7 4 The difference of the upper limit of the median class and the lower limit of the modal class is A0 (B) 19 (C) 20 (D) 38

(C) 20 Clarification: Class      Frequency           Cumulative Frequency   65-85     4             4   85-105  5             9   105-125               13           22  ...

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For the following distribution: Marks Number of students Below 10 3 Below 20 12 Below 30 27 Belo w 40 57 Below 50 75 Below 60 80 The modal class is (A)10-20 (B) 20-30 (C) 30-40 (D) 50-60

(C) 30-40 Clarification: Marks    Number of students        Cumulative Frequency   Underneath 10  3=3        3   10-20     (12 – 3) = 9         12   20-30     (27 – 12) = 15     27...

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For the following distribution : Class 0-05 5-10 10-15 15-20 20-25 Frequency 10 15 12 20 9 the sum of lower limits of the median class and modal class is (A)15 (B) 25 (C) 30 (D) 35

(B) 25 Clarification: Class      Frequency           Cumulative Frequency   0-5         10           10   5-10       15           25   10-15     12           37   15-20    ...

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While computing mean of grouped data, we assume that the frequencies are (A) Evenly distributed over all the classes (B) Centred at the class marks of the classes (C) Centred at the upper limits of the classes (D) Centred at the lower limits of the classes

(B) Centered at the class characteristics of the classes Clarification: In figuring the mean of assembled information, the frequencies are focused at the class signs of the classes. Subsequently,...

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Choose the correct answer from the given four options: 1. In the formula For finding the mean of grouped data di’s are deviations from a of (A) Lower limits of the classes (B) Upper limits of the classes (C) Mid points of the classes (D) Frequencies of the class marks

(C) Mid marks of the classes Clarification: We know, \[di\text{ }=\text{ }xi\text{ }\text{ }a\] Where, xi are information and 'a' is the expected to be mean In this way, di are the deviations from...

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