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Need Solution for R.D.Sharma Maths Class 12 Chapter 30 Probability  Exercise 30.5 Question 21 Maths Textbook Solution.

Answers (1)

Answer: \frac{2}{3}

Hint:  P=P\left ( A\cap B\cap \bar{C} \right )U\: P\left ( A\cap \bar{B}\cap{C} \right )U\: P\left ( \bar{A}\cap B\cap C \right )

Given: A can hit a target 3 times in 6 shots

B can hita target 2 times in 6 shots

C can hita target 4 times in 4 shots

Solution:

\begin{aligned} &P(\text { A hits the target })=\frac{3}{6}=\frac{1}{2} \\ &P(\mathrm{~B} \text { hits the target })=\frac{2}{6}=\frac{1}{3} \\ &P(\mathrm{C} \text { hits the target })=\frac{4}{4}=1 \end{aligned}

P (atleast 2 shots hit) = P(exactly 2 shots hit)+P(all 3 shots)

\begin{aligned} &=\frac{1}{2}\left(1-\frac{1}{3}\right)+\frac{1}{3}\left(1-\frac{1}{2}\right)+\frac{1}{2} \times \frac{1}{3} \times 1 \\ &=\frac{1}{2}\left(\frac{2}{3}\right)+\frac{1}{3}\left(\frac{1}{2}\right)+\frac{1}{6} \\ &=\frac{2}{6}+\frac{1}{6}+\frac{1}{6} \\ &=\frac{2}{6}+\frac{1}{6}+\frac{1}{6} \\ &=\frac{2+1+1}{6}=\frac{4}{6}=\frac{2}{3} \end{aligned}

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