Question

Worldwide, the proportion of babies who are boys is about 0.51 . Let the random variable X represent the number of boys in five children. Find the mean and standard deviation of this random variable.

Answer 1

mean = 2.55

Standard deviation = 1.118

Explanation:

Probability of babies who are boys

P = 0.51

Then we have q = 1-p

= 1-0.51

= 0.49

We have n = 5

We calculate the mean as:

np

= 0.51x5

= 2.55

Therefore mean = 2.55

The standard deviation

= √variance

= √npq

= √0.51x5x0.49

=√1.2495

= 1.118