Question

Pls help with this!!

A recent report in USA Today indicated a typical family of three
spends 420$ per month on food. Assume the distribution of food
follows the normal distribution with a mean of 420$ and a standard
deviation of 40$. What percent of the families spend more than 170$
but less than 670$ per month on food? What percent of the families
spend less than 380$ per month on food? What percent of the families
spend more between 400 and 500$ per month on food?

Answer 1

a)
Let X be the food expenditure of a family.
Let the population mean of an expenditure of a family be.
Let the population standard deviation of an expenditure of a family be.
The proportion families spend more than $30 but less than $490 per month on food is,