The probability that a teacher will give a surprise test in a class is 5 1 . If a student is absent twice, the probability that he will miss atleast one test will be 25 k , then k must be

Required probability = 1 − 5 4 × 5 4 = 25 9 ⇒ k = 9

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MathematicsProbabilityIndependent eventsMedium2 minQB

MathematicsMediumsingle choice

The probability that a teacher will give a surprise test in a class is $\frac{1}{5}$ . If a student is absent twice, the probability that he will miss atleast one test will be $\frac{k}{25}$ , then k must be

Answer:

Solution:

Required probability

$= 1 - \frac{4}{5} \times \frac{4}{5} = \frac{9}{25}$

$\Rightarrow k = 9$

Stream:JEESubject:MathematicsTopic:ProbabilitySubtopic:Independent events

⏱ 2mℹ️ Source: QB

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