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Please solve RD Sharma class 12 chapter Probability exercise 30.7 question 21 maths textbook solution

Answers (1)

Answer:

 \frac{1}{5}

Hint:

 Use Baye’s theorem.

Given:

 A bag contain 1 white and 6 red ball, and second bag contain 4 white 3 red. One of the bags is pick at random and ball is randomly drawn from college to white in color.

Solution:

Let E1, E2,E3 be event

E1 = E2 = Selection of bag,

A=The white ball drawn random

\begin{aligned} &P(E_1)=\frac{1}{2}\\ &P(E_2)=\frac{1}{2}\\ &P\left ( \frac{A}{E_1} \right )=\frac{1}{7}\\ &P\left ( \frac{A}{E_2} \right )=\frac{4}{7}\\ \end{aligned}

Using Baye’s theorem we get

\begin{aligned} &P\left (\frac{E_1}{A} \right )=\frac{P(E_1).P\left ( \frac{A}{E_1} \right )}{P(E_1)\times P\left ( \frac{A}{E_1} \right )+P(E_2)\times P\left ( \frac{A}{E_2} \right )}\\ &=\frac{{\frac{1}{2}\times \frac{1}{7} }}{\frac{1}{2}\times \frac{1}{7}+\frac{1}{2}\times \frac{4}{7}}\\ &=\frac{1}{1+4}\\ &=\frac{1}{5} \end{aligned}

Posted by

Gurleen Kaur

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