Before a New Phone System Was Installed, the Amount a Company

Multiple Choice

Before a new phone system was installed, the amount a company spent on personal calls followed a normal distribution with an average of $700 per month and a standard deviation of $50 per month. Refer to such expenses as PCE's (personal call expenses) . Find the probability that a randomly selected month had PCE's below $550.

A) 0.0013
B) 0.7857
C) 0.2143
D) 0.9987