Confidence Interval and Standard Deviation
I can't get these ones at all x.x please help
ABC College Bookstore sells Ti83 calculators. The random number of calculators sold per day along with the probabilities is:
# of calculators: 1, 2, 3, 4, 5
Probability: 1/8, 1/6, 1/2, 1/12, 1/8
What is the standard deviation for the number of calculators sold?
Find a 95% confidence interval for the mean weight of bass caught in El Capitan lake if a sample of 300 fish had a mean weight of 77 ozs. with a standard deviation of 12 ozs.
I've been trying to figure these out for a while and still can't get it right. :(