Calculate the expected value, the variance, and the standard deviation of the given random variableX. (Round all answers to two decimal places.)Xis the number of red marbles that Suzan has in her hand after she selectsthreemarbles from a bag containingthreered marbles and two green ones. Find the following:

expected value=

variance=

standard deviation=

According to a study, the probability that a randomly selected teenager shopped at a mall at least once during a week was0.67. LetXbe the number of students in a randomly selected group of60that will shop at a mall during the next week.

(a) Compute the expected value and standard deviation ofX. (Round your answer to two decimal places.) Hint [See Example 5.]

expected value=

standard deviation=

(b) Fill in the missing quantity. (Round your answer to the nearest whole number.)

There is an approximately 2.5% chance that________or more teenagers in the group will shop at the mall during the next week.