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

Question

Quizplus · Accepted Answer

To find the probability that PCE's are below $550, we calculate the z-score: z = (550 - 700) / 50 = -3. Using the standard normal distribution table, the probability of z being less than -3 is approximately 0.0013.

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