Q15 of 99 Page 33

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.


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