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According to the internal revenue service, income tax returns one year averaged $1,332 (one thousand three hundred and thirty two dollars) in refunds for taxpayers . One explination of this figure is that taxpayers woudl rather have the government keep back too much money during the year tan to ow it money at the end of the year. Suppose the average amount of tax at the end of a year is a refund of $1,332, with a standard deviation of $725. Assume that amounts owed or due on tax returns are normally distributed.

a. What proportion of tax returns show a refund greater tahn $2,000?

b. What proportion of the tax return show that the taxpayers owe money to the government ?

c. What proportion os the tax returns show a refund between $100 and $750?