The amount of fuel used each week by a real estate agent dri

The amount of fuel used each week by a real estate agent driving po-

tential home-buyers around the city to inspect houses was found to

approximate a normal distribution with mean = 75 litres and stan-

dard deviation = 15 litres. For a 200 week period determine the

expected number of weeks the fuel consumption was in the following

ranges (assume litres are measured on a continuous scale):

(a) less than 80 litres;

(b) more than 90 litres;