A random sample of math majors taking an introductory statistics course were surveyed after completing thefinal exam. They were asked, "How many times did you review your final exam before handing it in to the professor?" The results are displayed in a probability density function for the random variable X, the number of times students reviewed their exam before handingit in. Find the standard deviation of X.

• Round the final answer to two decimal places.

x	P(X = x)
1	1/5
2	2/5
7	2/5