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Need solution for RD Sharma maths class 12 chapter Probability exercise 30.7 question 11

Answers (1)

Answer:

 i)\: \frac{3}{19}, \quad (ii)\frac{6}{19}, \quad (iii)\frac{10}{19}

Hint:

 Use baye’s theorem.

Given:

 An insurance company is used 3000, 4000, 5000 trucks. The probability of accident involving a scooter, a car, a truck 0.02, 0.03, 0.04, one insured vehicle meets with accident. Find the probability of (i) Scooter, (ii) car, (iii)Truck

Solution:

Let E1,E2,E3 denote the event that vehicle is (i) Scooter, (ii) car, (iii) Truck.

Let A be event that vehicle meet an accident.

It is given that 3000 scooter, 4000 car and 5000 truck.

Total vehicle = 3000 + 4000 + 5000 = 12000

\begin{aligned} &P(E_1)=\frac{3000}{12000}=\frac{1}{4}\\ &P(E_2)=\frac{4000}{12000}=\frac{1}{3}\\ &P(E_3)=\frac{5000}{12000}=\frac{5}{12}\\ &P\left ( \frac{A}{E_1} \right )=0.02=\frac{2}{100}\\ &P\left ( \frac{A}{E_2} \right )=0.03=\frac{3}{100}\\ &P\left ( \frac{A}{E_3} \right )=0.04=\frac{4}{100}\\ \end{aligned}

Using Baye’s theorem we get

Required probability

\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 )+P(E_3)\times P\left ( \frac{A}{E_3} \right )}\\ &=\frac{{\frac{1}{4}\times \frac{2}{100} }}{\frac{1}{4}\times \frac{2}{100}+\frac{1}{3}\times \frac{3}{100}+\frac{5}{12}\times \frac{4}{100}}\\ &=\frac{\frac{1}{2}}{\frac{1}{2}+1+\frac{5}{3}}\\ &=\frac{\frac{1}{2}}{\frac{3+6+10}{6}}\\ &=\frac{3}{19} \end{aligned}

Required probability

\begin{aligned} &P\left (\frac{E_2}{A} \right )=\frac{P(E_2).P\left ( \frac{A}{E_2} \right )}{P(E_1)\times P\left ( \frac{A}{E_1} \right )+P(E_2)\times P\left ( \frac{A}{E_2} \right )+P(E_3)\times P\left ( \frac{A}{E_3} \right )}\\ &=\frac{{\frac{1}{3}\times \frac{3}{100} }}{\frac{1}{4}\times \frac{2}{100}+\frac{1}{3}\times \frac{3}{100}+\frac{5}{12}\times \frac{4}{100}}\\ &=\frac{1}{\frac{1}{2}+1+\frac{5}{3}}\\ &=\frac{1}{\frac{3+6+10}{6}}\\ &=\frac{6}{19} \end{aligned}

Required probability

\begin{aligned} &P\left (\frac{E_3}{A} \right )=\frac{P(E_3).P\left ( \frac{A}{E_3} \right )}{P(E_1)\times P\left ( \frac{A}{E_1} \right )+P(E_2)\times P\left ( \frac{A}{E_2} \right )+P(E_3)\times P\left ( \frac{A}{E_3} \right )}\\ &=\frac{{\frac{5}{12}\times \frac{4}{100} }}{\frac{1}{4}\times \frac{2}{100}+\frac{1}{3}\times \frac{3}{100}+\frac{5}{12}\times \frac{4}{100}}\\ &=\frac{\frac{5}{3}}{\frac{1}{2}+1+\frac{5}{3}}\\ &=\frac{\frac{5}{3}}{\frac{3+6+10}{6}}\\ &=\frac{10}{19} \end{aligned}

Posted by

Gurleen Kaur

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