1.

Let x represent the number of times a student visits a gym in a one month period. Assume that the probability distribution of X is as follows:

x 0 1 2 3

p(x) 0.37 0.29 0.22 0.12

Find the mean, mu , of this distribution. Report your answer to two decimal places.

2.

The random variable X represent the number of horses per family in a rural area in Iowa, given below:

x 2 3 4 5 6

p(x) 0.10 0.15 0.20 0.25 0.30

Determine the standard deviation of X. Report your answer to three decimal places.

3.

It is said that sufferers of a cold virus experience symptoms for 6 days. However, the amount of time is actually a normally distributed random variable which has a mean of 5.5 days and which has a standard deviation of 1.8 days. What proportion of cold sufferers experience fewer than 5 days of symptoms? Report your answer to four decimal places.