Mathematics - Probability Question with Solution | TestHub

MathematicsProbabilityConditional probabilityHard2 minPYQ_2017

MathematicsHardsingle choice

If the papers of $4$ students can be checked by any one of the $7$ teachers, then the probability that all the $4$ papers are checked by exactly $2$ teachers, is equal to

Options:

Answer:

Solution:

Total ways in which papers can be checked is equal $7^{4}$ . Now, two teachers who have to check all the papers can be selected in ${}^{7}C_{2}$ ways and papers can be checked by them is $(2^{4} - 2)$ favourable ways.

Thus, required probability

$= \frac{{}^{7}C_{2} (2^{4} - 2)}{7^{4}} = \frac{6}{49}$

Stream:BITSATSubject:MathematicsTopic:ProbabilitySubtopic:Conditional probability

⏱ 2mℹ️ Source: PYQ_2017

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