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15

A die is thrown thrice. A success is 1 or 6 in a throw. Find the mean and variance of the number of successes.

Let p be the probability of success

∴ the p = probability of getting 1 or 6

Given, n = 3

Mean = np

= 1

Variance = npq

= 0.66

Therefore, mean = 1, standard deviation = 0.66.