Question

Can someone please check my answer? I will fan and medal!

Answer 1

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 6% of 80%.

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 2

My answer:
The confidence interval is 90% because as stated in the question: 9 out of 10.

The margin of error is 4.8%.
This is calculated by:
80×6/ 100=4.8

we have a 90% confidence interval meaning 0.06 < p < 0.80 where p is the population.

Answer 3

A confidence interval gives the likely range for a population parameter based on sample information. This interval is formed using the standard normal probability distribution, assuming that the sample size was 30 or greater. In the given situation we can say that a 90% confidence interval for the average score of the population is (75.2%, 84.8%) and 90% of such intervals will contain the average score of the population.

Answer 4

So I can incorporate that into my answer and it will be good to go? @kropot72 Thank you so much btw ;v;

Answer 5

Yes you can. But don't include your following sentence:
"we have a 90% confidence interval meaning 0.06 < p < 0.80 where p is the population. "

Answer 6

Okay gotcha! What you gave me would suffice for that instead correct? Anything else I need to fix? @kropot72

Answer 7

Correct. The rest is correct.

Answer 8

thank you so much! I really appreciate it ;;v;;!! @kropot72

Answer 9

You're welcome :)