Question

A field test for a new exam was given to randomly selected seniors. The exams were graded, and the sample mean and sample standard deviation were calculated. Based on the results, the exam creator claims that on the same exam, nine times out of ten, seniors will have an average score within 5% of 75%.

Is the confidence interval at 90%, 95%, or 99%? What is the margin of error? Calculate the confidence interval and explain what it means in terms of the situation.

Answer 1

@amistre64 Sorry to bother you, but I was also stuck on this question.

Answer 2

Nine times out of ten means 90%
It is the confidence interval at 90%
The confidence interval is (5%, 75%)
It means the population mean is said with 90% confidence level to fall within the interval 5% to 75%
Margin of error = (upper bound - lower bound) / 2
= (75% - 5%) / 2
= 35% or 0.35

Answer 3

o-o" Why, thank you...