Two companies, A and B, drill wells in a rural area. Company A charges a flat fee of $3500 to drill a well regardless of its depth. Company B charges $1000 plus $12 per foot to drill a well. The depths of wells drilled in this area have a normal distribution with a mean of 250 feet and a standard deviation of 40 feet.
a. What is the probability that Company B would charge more than Company A to drill a well?
b. Find the mean amount charged by Company B to drill a well.