A recent report in USA today indicated a typical family of four spends $490 per month on food. Assume the distribution of food expenditures for a family of four follows the normal distribution, with a mean of $490 and a standard deviation of $90.

a. What percent of the families spend more than $30 but less than $490 per month on food?

b. What percent of the families spend less than $430 per month on food?

c. What percent spend between $430 and $600 per month on food?

d. What percent spend between $500 and $600 per month on food?