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

@Vocaloid Please help!

Answer 2

@ganeshie8 Can you help please?

Answer 3

How much percentage is 9 out of 10 ?

Answer 4

90%

Answer 5

Yes
So that would be the confidence interval

Answer 6

ok, what about the margin of error?

Answer 7

Simply find 5 percent of 75

Answer 8

5% times 75?

Answer 9

Yes

Answer 10

so 3.75?

Answer 11

Looks good
That is the margin of error

Answer 12

ok, finally what is the confidence interval and can you explain it in the terms of this situation please?

Answer 13

As the name says it us an interval.

To get the lower value, subtract margin of error from 75

To get the upper value, add margin of error to 75

Answer 14

Ohhhhhh. I forgot! Then how do you explain this in the situation?

Answer 15

Could you tell me the confidence interval first

Answer 16

sure it is 71.25-78.75

Answer 17

Yep

Answer 18

how do you explain this in the situation?

Answer 19

Here is the explanation :

If you take many samples and calculate the average value, we can say that 90 percent of those samples will have average value between 71.25 and 78.75

Answer 20

This has helped me alot. Thank you, if i have another question later can you help me?

Answer 21

I'll try
You're welcome

Answer 22

Thank you! Your a lifesaver!!!