Question

3. You hear a claim that the average score on a national exam is higher than it used to be, which is 77. Of course you response is "Oh it is, huh? We'll see about that!" You test this claim by getting a random sample of 60 exam scores for this national exam. The sample mean is 80 and the sample standard deviation is 8.2.

Be sure to check if the conditions are met, and show how you checked them

3a) Test this claim at the α =0.01 level of significance.

whats your conclusion?

3b) Find a 90% confidence interval for the mean of all exam scores for this national exam.

state your answer in words:

3c) How large of a sample is needed in order to have a confidence level of 98%with a margin of error 1 point?

Use σ ≈ 8.2 sample size n=?

Answer 1