Falcon Chocolates makes quality chocolate products and sells its products through a website. You work in Falcon's marketing department and your team has been tasked with developing new strategies to increase the company's internet sales. Using the data from last year, you found the following information:

75% of the transactions were conducted using Explorer as the web browser;

the time spent on the company's website was normally distributed with a mean of 7 minutes per transaction and a standard deviation of 1.3 minutes per transaction.

the amount spent was normally distributed with a mean of $72 per transaction and a standard deviation of $12.50 per transaction.

You assume this information has not changed this year.

Suppose 500 transactions are taken from the company's website.

(a) What is the probability that the sample mean amount is less than $73.25? (show work)