Question

9) Professor Elderman has given the same multiple-choice final exam in his Principles ofMicroeconomics class for many years. After examining his records from the past 10 years, hefinds that the scores have a mean of 76 and a standard deviation of 12.Professor Elderman offers his class of 36 a pizza party if the class average is above 80. What isthe probability that he will have to deliver on his promise?

Answer 1

In this case, we'll have to carry out several steps to find the solution.

Step 01:

data:

score:

mean = 76

standard deviation = 12

Step 02:

probability:

normal distribution:

normal distribution diagram:

mean + 1 standard deviation = 76 + 12 = 88

probability (class average score is above 80):

p (score > 80) = 34% + 13.5% + 2.4% + 0.1% = 50% = 0.5

The answer is:

p (score > 80) = 50% = 0.5