Given : let $\mathrm{H}$ be head, and $\mathrm{T}$ be tails where as $1,2,3,4,5,6$ be the numbers on the dice which are thrown when a head comes up or else coin is tossed again if its tail....
A coin is tossed. If a head comes up, a die is thrown, but if a tail comes up, the coin is tossed again. Find the probability of obtaining
(i) two tails
(ii) a head and the number 6
Given : let $\mathrm{H}$ be head, and $\mathrm{T}$ be tails where as $1,2,3,4,5,6$ be the numbers on the dice which are thrown when a head comes up or else coin is tossed again if its tail....
Let and be two the switches and let their probabilities of working be given by and Find the probability that the current flows from terminal A to terminal , when and are installed in parallel, as shown below:
Solution: Given: $\mathrm{S}_{1}$ and $\mathrm{S}_{2}$ are two swiches whose probabilities of working be given by $\mathrm{P}\left(\mathrm{S}_{1}\right)=\frac{2}{3}$ and...
Let and be the two switches and let their probabilities of working be given by and . Find the probability that the current flows from the terminal A to terminal B when and are installed in series, shown as follows:
Solution: Given: $S_{1}$ and $S_{2}$ are two swiches whose probabilities of working be given by $\mathrm{P}\left(\mathrm{S}_{1}\right)=\frac{4}{5} \text { and }...
An anti-aircraft gun can take a maximum of 4 shots at an enemy plane moving away from it. The probabilities of hitting the plane at the first, second, third and fourth shots are and respectively. What is the probability that at least one shot hits the plane?
Given:Let $A, B, C$ and $D b e$ first second third and fourth shots whose probability of hitting the plane is given i.e, $\mathrm{P}(\mathrm{A})=0.4, \mathrm{P}(\mathrm{B})=0.3,...
A machine operates only when all of its three components function. The probabilities of the failures of the first, second and third components are and , respectively. What is the probability that the machine will fail?
Given: let $A, B$ and $C$ be the three components of a machine which works only if all its three compenents function.the probabilities of the failures of $A, B$ and $C$ respectively is given i.e,...
A town has two fire-extinguishing engines, functioning independently. The probability of availability of each engine when needed is What is the probability that
(i) neither of them is available when needed?
(ii) an engine is available when needed?
Given: Let $A$ and $B$ be two fire extinguishing engines. The probability of availability of each of the two fire extinguishing engines is given i.e., $\mathrm{P}(\mathrm{A})=0.95$ and...
An article manufactured by a company consists of two parts and . In the process of manufacture of part X. 8 out of 100 parts may be defective. Similarly, 5 out of 100 parts of may be defective. Calculate the probability that the assembled product will not be defective.
Given: $X$ and $Y$ are the two parts of a company that manufactures an article. Here the probability of the parts being defective is given i.e, $\mathrm{P}(\mathrm{X})=\frac{8}{100}$ and...
Neelam has offered physics, chemistry and mathematics in Class XII. She estimates that her probabilities of receiving a grade in these courses are and respectively. Find the probabilities that Neelam receives exactly 2 A grades.
Given : let $A, B$ and $C$ represent the subjects physics,chemistry and mathematics respectively ,the probability of neelam getting $A$ grade in these three subjects is given i.e, $P(A)=0.2,...
Neelam has offered physics, chemistry and mathematics in Class XII. She estimates that her probabilities of receiving a grade in these courses are and respectively. Find the probabilities that Neelam receives
(i) all A grades
(ii) no A grade
Given : let $A, B$ and $C$ represent the subjects physics,chemistry and mathematics respectively ,the probability of neelam getting $A$ grade in these three subjects is given i.e, $P(A)=0.2,...
A can hit a target 4 times in 5 shots, B can hit 3 times in 4 shots, and can hit 2 times in 3 shots. Calculate the probability that
(i) and all hit the target
(ii) and hit and does not hit the target.
Given : let $A, B$ and $C$ chances of hitting a target is given i.e, $P(A)=\frac{4}{5}, P(B)=\frac{3}{4}$ and $P(C)=\frac{2}{3}$ $\Rightarrow \mathrm{P}(\bar{A})=\frac{1}{5},...
The probabilities of solving a problem are and , respectively. If all the three try to solve the problem simultaneously, find the probability that exactly one of them will solve it.
Given : let $A, B$ and $C$ be three students whose chances of solving a problem is given i.e, $P(A)=\frac{1}{3}, P(B)=\frac{1}{4}$ and $P(C)=\frac{1}{6}$ $\Rightarrow...
A problem is given to three students whose chances of solving it are and , respectively. Find the probability that the problem is solved.
Given : let $A, B$ and $C$ be three students whose chances of solving a problem is given i.e, $P(A)=\frac{1}{4}, P(B)=\frac{1}{5}$ and $P(C)=\frac{1}{6}$ $\Rightarrow...
Given the probability that A can solve a problem is , and the probability that B can solve the same problem is \%, find the probability that
(i)at least one of and will solve the problem
(ii)none of the two will solve the problem
Given : Here probability of $A$ and $B$ that can solve the same problem is given, i.e., $P(A)=\frac{2}{3}$ and $P(B)=\frac{3}{5} \Rightarrow P($ $\bar{A})=\frac{1}{3}$ and...
A and B appear for an interview for two vacancies in the same post. The probability of A’s selection is and that of B’s selection is Find the probability that
(i) none is selected
(ii) at least one of them is selected.
Given : $A$ and $B$ appear for an interview, then $P(A)=\frac{1}{6}$ and $P(B)=\frac{1}{4} \Rightarrow P(\bar{A})=\frac{5}{6}$ and $P(\bar{B})=\frac{3}{4}$ Also, $A$ and $B$ are independent. A and...
A and B appear for an interview for two vacancies in the same post. The probability of A’s selection is and that of B’s selection is Find the probability that
(i) both of them are selected
(ii) only one of them is selected
Given : $A$ and $B$ appear for an interview, then $P(A)=\frac{1}{6}$ and $P(B)=\frac{1}{4} \Rightarrow P(\bar{A})=\frac{5}{6}$ and $P(\bar{B})=\frac{3}{4}$ Also, $A$ and $B$ are independent. A and...
Arun and Ved appeared for an interview for two vacancies. The probability of Arun’s selection is , and that of Ved’s rejection is Find the probability that at least one of them will be selected.
Given : let A denote the event 'Arun is selected' and let B denote the event 'ved is selected'. Therefore, $\mathrm{P}(\mathrm{A})=\frac{1}{4}$ and $\mathrm{P}(\bar{B})=\frac{2}{3} \Rightarrow...
Kamal and Vimal appeared for an interview for two vacancies. The probability of Kamal’s selection is , and that of Vimal’s selection is Find the probability that only one of them will be selected.
event 'vimal is selected'. Therefore, $\mathrm{P}(\mathrm{A})=\frac{1}{3}$ and $\mathrm{P}(\mathrm{B})=\frac{1}{5}$ Also, $A$ and $B$ are independent .A and not $B$ are independent, not $A$ and $B$...
Let and be the events such that and or .
State whether A and B are
(i) mutually exclusive
(ii) independent
Given: $A$ and $B$ are the events such that $P(A)=\frac{1}{2}$ and $P(B)=\frac{7}{12}$ and $P(\operatorname{not} A$ or $\operatorname{not} B)=\frac{1}{4}$ To Find: i)if A and B are mutually...
If and are independent events such that and , find
(i)
(ii)
i) $\mathrm{P}\left(\overline{E_{1}} \cap \overline{E_{2}}\right)=\mathrm{P}\left(\overline{E_{1}}\right) \times \mathrm{P}\left(\overline{E_{2}}\right)$ since, $P\left(E_{1}\right)=0.3$ and...
If and are independent events such that and , find
(i)
(ii)
i) $P\left(E_{1} \cap E_{2}\right)$ We know that, when $E_{1}$ and $E_{2}$ are independent, $\begin{array}{l} P\left(E_{1} \cap E_{2}\right)=P\left(E_{1}\right) \times P\left(E_{2}\right) \\ =0.3...
If and are the two events such that and , show that and are independent events.
We know that, Hence, $P\left(E_{1} \cap E_{2}\right)=P\left(E_{1}\right)+P\left(E_{2}\right)-P\left(E_{1} \cup E_{2}\right)$ $=\frac{1}{4}+\frac{1}{3}-\frac{1}{2}$ $=\frac{1}{12}$ Equation 1 Since...
Let and be the events such that and . Find:
(i) , when and are mutually exclusive.
(ii) , when and are independent
(i) We know that, When two events are mutually exclusive $P\left(E_{1} \cap E_{2}\right)=0$ Hence, $P\left(E_{1} \cup E_{2}\right)=P\left(E_{1}\right)+P\left(E_{2}\right)$ $\begin{array}{l}...
An urn contains 5 white and 8 black balls. Two successive drawings of 3 balls at a time are made such that the balls drawn in the first draw are not replaced before the second draw. Find the probability that the first draw gives 3 white balls and the second draw gives 3 black balls.
Let, success in the first draw be getting 3 white balls. Now, the Probability of success in the first trial is $P_{1}(\text { success })=\frac{5_{c_{3}}}{13_{c_{3}}}=\frac{10}{286}=\frac{5}{143}$...
A bag contains white and 15 black balls. Two balls are drawn in succession without replacement. What is the probability that the first ball is white and the second is black?
Let, success in the first draw be getting a white ball. Now, the Probability of success in the first trial is $\mathrm{P}_{1}(\text { success })=\frac{10}{25}$ Let success in the second draw be...
There is a box containing 30 bulbs, of which 5 are defective. If two bulbs are chosen at random from the box in succession without replacing the first, what is the probability that both the bulbs are chosen are defective?
Let, success :bulb chosen is defective .i.e $\frac{5}{30}$ Now, the Probability of success in the first trial is $P_{1}(\text { success })=\frac{5}{30}$ Probability of success in the second trial...
A card is drawn from a well-shuffled deck of 52 cards and without replacing this card, a second card is drawn. Find the probability that the first card is a club and the second card is a spade.
Let, success for the first trail be getting a club. Now, the Probability of success in the first trial is $\mathrm{P}_{1} \text { (success) }=\frac{13}{52}$ let, success for the second trail be...
Two marbles are drawn successively from a box containing 3 black and 4 white marbles. Find the probability that both the marbles are black if the first marble is not replaced before the second draw.
Let, success : marble drawn is black.i.e Number of black marbles/Total number of marbles $=\frac{3}{7}$ Now, the Probability of success in the first trial is $P_{1}(\text { success })=\frac{3}{7}$...
A bag contains 17 tickets, numbered from 1 to 17 . A ticket is drawn, and then another ticket is drawn without replacing the first one. Find the probability that both the tickets may show even numbers.
Let, success : ticket drawn is even.i.e $\frac{8}{17}$ Now, the Probability of success in the first trial is $P_{1}(\text { success })=\frac{8}{17}$ Probability of success in the second trial...