Question: Last January 1, Jenny thought about buying individual stocks. Over the next year, the mean of the percentage changes in individual stock prices is 6.5% and the standard deviation of these percentage changes is 12.8%. The distribution of price changes is approximately normal.

a. If Jenny had picked one stock at random, what is the probability that it would have gone down in price?

b. If Jenny had picked four stocks at random, what is the probability that their mean percentage changes would be negative?

c. If Jenny had picked eight stocks at random, what is the probability that their mean percentage change would be between 8% and 10%?

d. If Jenny had picked eight stocks at random, what mean percentage changes in price are reasonably likely