The mean amount of gas and services charged by Key Refining Company credit consumers is $80 per month. The distribution of amounts spent is approximately normal with a standard deviation of $13.
a) Compute the probability of selecting a consumer at random and finding the consumer charged between $70 and $85 last month. Sketch the region on the standard normal curve that we're looking for.
b) Again using the Key Refining data from problem # 6 compute the probability of a customer charging between $56 and $85per month. Sketch this region of interest on the standard normal curve.
c) Using the KEY REFINING data from problem # 6, what is the probability that a particular customer charges less than $50? Sketch the region of interest on the STD. NORMAL CURVE.