Q11 of 105 Page 576

Find the probability of getting 5 exactly twice in 7 throws of a die.

In this question, let us assume X represent the number of times of getting 5 in 7 throws of the die

Also, the repeated tossing of a die are the Bernoulli trials


Thus, probability of getting 5 in a single throw,


And,




Clearly, we have X has the binomial distribution where n = 7 and


∴



Hence, probability of getting 5 exactly twice in a die = P (X = 2)





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