The IRS reports that the mean refund for a particular group of taxpayers was $1,600. The distribution of tax refunds follows a normal distribution with a standard deviation of $850.
Required:
a. What percentage of the refunds are between $1,600 and $2,000?
b. What percentage of the refunds are between $900 and $2,000?
c. What percentage of the refunds are between $1,800 and $2,000?
d. Ninety-five percent of the refunds are for less than what amount?