violin instructor wants to determine the percent of her students that will continue taking classes with her each year. Let

X = The number of years that a student will study violin with this teacher,

P(X) = The probability that a student will study violin for X number of years.

X	1	2	3	4	5
P(X = x)	0.4	0.25	0.2	0.1	0.05

1. How many years should the teacher be able to expect a student to take lessons with her?

2. What is the standard deviation for this random variable?