Find and Interpret the Area under a Normal Curve
-A new phone system was installed last year to help reduce the expense of personal calls that were being made by employees. Before the new system was installed, the amount being spent on personal calls follows 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 a PCE that falls below $550.
A) 0.0013
B) 0.7857
C) 0.2143
D) 0.9987

Question

Quizplus · Accepted Answer

The Z-score for $550 is calculated as (550 - 700) / 50 = -3. Using the standard normal distribution table, the probability of a Z-score below -3 is approximately 0.0013.

Find and Interpret the Area Under a Normal Curve