Exercise 1

In an examination, the number of those who passed and the number of those who failed were in the ratio of

    \[3:1\]

. Had

    \[8\]

more appeared, and

    \[6\]

less passed, the ratio of passed to failures would have been

    \[2:1\]

. Find the number of candidates who appeared.

Consider the number of passed = \[3x\] Number of failed = x So the total candidates appeared = \[3x\text{ }+\text{ }x\text{ }=\text{ }4x\] In the second case Number of candidates appeared =...

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(i) The monthly pocket money of Ravi and Sanjeev are in the ratio

    \[5:7\]

. Their expenditures are in the ratio

    \[3:5\]

. If each saves Rs

    \[80\]

per month, find their monthly pocket money. (ii) In class X of a school, the ratio of the number of boys to that of the girls is

    \[4:3\]

. If there were

    \[20\]

more boys and

    \[12\]

less girls, then the ratio would have been

    \[2:1\]

. How many students were there in the class?

(i) Consider the monthly pocket money of Ravi and Sanjeev as \[5x\] and \[7x\] Their expenditure is \[3y\] and \[5y\] respectively. \[5x\text{ }\text{ }3y\text{ }=\text{ }80\] …… (1) \[7x\text{...

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(i) In a mixture of

    \[45\]

litres, the ratio of milk to water is

    \[13:2\]

. How much water must be added to this mixture to make the ratio of milk to water as

    \[3:1\]

? (ii) The ratio of the number of boys to the numbers of girls in a school of

    \[560\]

pupils is

    \[5:3\]

. If

    \[10\]

new boys are admitted, find how many new girls may be admitted so that the ratio of the number of boys to the number of girls may change to

    \[3:2\]

.

(i) It is given that Mixture of milk to water = \[45\] litres Ratio of milk to water = \[13:2\] Sum of ratio = \[13\text{ }+\text{ }2\text{ }=\text{ }15\] Here the quantity of milk = \[\left(...

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(i) A certain sum was divided among A, B and C in the ratio

    \[7:5:4\]

. If B got Rs

    \[500\]

more than C, find the total sum divided. (ii) In a business, A invests Rs

    \[50000\]

for

    \[6\]

months, B Rs

    \[60000\]

for

    \[4\]

months and C Rs

    \[80000\]

for

    \[5\]

months. If they together earn Rs

    \[18800\]

find the share of each.

(i) It is given that Ratio between A, B and C = \[7:\text{ }5:\text{ }4\] Consider A share = \[7x\] B share = \[5x\] C share = \[4x\] So the total sum =\[~7x\text{ }+\text{ }5x\text{ }+\text{...

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(i) A woman reduces her weight in the ratio

    \[7:5\]

. What does her weight become if originally it was

    \[91\]

kg. (ii) A school collected Rs 2100 for charity. It was decided to divide the money between an orphanage and a blind school in the ratio of 3: 4. How much money did each receive?

(i) Ratio of original and reduced weight of woman = \[7:5\] Consider original weight = \[7x\] Reduced weight = \[5x\] Here original weight = \[91\]  kg So the reduced weight = \[~\left( 91\text{...

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(i) Find two numbers in the ratio of

    \[\mathbf{8}:\text{ }\mathbf{7}\]

such that when each is decreased by

    \[\mathbf{12}\text{ }{\scriptscriptstyle 1\!/\!{ }_2}\]

, they are in the ratio

    \[\mathbf{11}:\text{ }\mathbf{9}\]

. (ii) The income of a man is increased in the ratio of

    \[\mathbf{10}:\text{ }\mathbf{11}\]

. If the increase in his income is Rs

    \[\mathbf{600}\]

per month, find his new income.

(i) Ratio = \[\mathbf{8}:\text{ }\mathbf{7}\] Consider the numbers as \[8x\] and \[7x\] Using the condition \[\left[ 8x\text{ }\text{ }25/2 \right]/\text{ }\left[ 7x\text{ }\text{ }25/2...

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