not sure why my answer is wrong. i did all the calucations.

Myers Business Systems is evaluating the introduction of a new product. The possible levels of unit sales and the probabilities of their occurrence are given next TT Possible Market Reaction Low response Moderate response High response Very high response Sales in Units 40 55 65 80 Probabilities 10 20 20 50 a. What is the expected value of unit sales for the new product? (Do not round intermediate calculations and round your answer to the nearest whole unit.) Expected value 192 units b. What is the standard deviation of unit sales? (Do not round intermediate calculations. Round your answer to 2 decimal places.) Standard deviation 13.87 units