All the major stock market indexes posted strong gains in 2009. The mean one-year return for stocks

Question:

All the major stock market indexes posted strong gains in 2009. The mean one-year return for in the S&P 500, a group of 500 very large companies, was 23.45%. The mean one-year return for the NASDAQ, a group of 3,200 small and medium-sized companies, was 43.89%. Historically, the one-year returns are approximately normally distributed, the standard deviation in the S&P 500 is approximately 20%, and the standard deviation in the NASDAQ is approximately 30%.
a. What is the probability that a stock in the S&P 500 gained value in 2009?
b. What is the probability that a stock in the S&P 500 gained 10% or more?
c. What is the probability that a stock in the S&P 500 lost 20% or more in 2009?
d. What is the probability that a stock in the S&P 500 lost 40% or more?
e. Repeat (a) through (d) for a stock in the NASDAQ.
f. Write a short summary on your findings. Be sure to include a discussion of the risks associated with a large standard deviation.
Stocks
Stocks or shares are generally equity instruments that provide the largest source of raising funds in any public or private listed company's. The instruments are issued on a stock exchange from where a large number of general public who are willing...