Get Answers to all your Questions

header-bg qa

Please Solve R.D.Sharma class 12 Chapter 30 Probaility  Exercise 30.5 Question 10 Maths Textbook Solution.

Answers (1)

Answer:\frac{1}{3}

Hint: You must know the rules of finding probability and G.P series

Given: A and B toss a coin alternately till one of them get a heads and wins thegame

Solution: If A starts the game, then B will win only at even positions

P(winning the game) = P(head at 2nd turn + 4th turn + …….)

\begin{aligned} &\Rightarrow\left(\frac{1}{2} \times \frac{1}{2}\right)+\left(\frac{1}{2}\right)\left(\frac{1}{2}\right)\left(\frac{1}{2}\right)\left(\frac{1}{2}\right)+\ldots \ldots \ldots . \\\\ &=\left(\frac{1}{2}\right)^{2}+\left(\frac{1}{2}\right)^{4}+\left(\frac{1}{2}\right)^{6}+\ldots \ldots . . \\\\ &\Rightarrow \frac{1}{4}\left[1+\left(\frac{1}{2}\right)^{2}+\left(\frac{1}{2}\right)^{4}+\ldots .\right] \\\\ &\Rightarrow \frac{1}{4}\left[\frac{1}{1-\frac{1}{4}}\right] \quad\left[\text { For G.P: } 1+a+a^{2}+a^{3}+\ldots=\frac{1}{1-a}\right] \\\\ &\Rightarrow \frac{1}{4} \times \frac{4}{3} \\\\ &\Rightarrow \frac{1}{3} \end{aligned}

Posted by

infoexpert21

View full answer

Crack CUET with india's "Best Teachers"

  • HD Video Lectures
  • Unlimited Mock Tests
  • Faculty Support
cuet_ads