JEE Main 2007 — Probability Question with Solution
JEE Main 2007
Question
Two aeroplanes I and II bomb a target in succession. The probabilities of I and II scoring a hit correctly are and , respectively. The second plane will bomb only if the first misses the target. The probability that the target is hit by the second plane is
Choose an option
Show full solutionCorrect option: D
Correct answer
DNone of these
Step-by-step explanation
The desired probability
$\begin{aligned}
& =0.7 \times 0.2+(0.7)(0.8)(0.7)(0.2)+(0.7)(0.8)(0.7)(0.8)(0.7)(0.2)+\ldots . \\
& =0.14\left[1+(0.56)+(0.56)^2+\ldots\right] \\
& =0.14\left[\frac{1}{1-0.56}\right]=\frac{0.14}{0.44}=\frac{7}{22}.
\end{aligned}$
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This is a previous-year question from JEE Main 2007, covering the Probability chapter of Mathematics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.