Question: You know percentage daily increases in value of stocks in ten randomly selected days at stock market.

10%, 16%, 5%, 10%, 12%, 8%, 4%, 6%, 5%, 4%.

We assume that the percentage daily increase in value is a random variable with a normal distribution.

a) Find a 95% confidence interval for mean of daily increases in value!

b) Find a 90% confidence interval for standard deviation of daily increases in value!