In: Statistics and Probability
Hey the correct answer is given for both, but can you please do the steps on how to get to the answer, Im confused on how to solve? Thank you!
3. At least what sample size is necessary in order to obtain a 90% confidence interval of length 6, when SD = 10?
A. 8 B. 16 C. 60 D. 15 E. 61 Answer: E
4. With which combination of confidence level and sample size will the corresponding confidence interval be largest?
A. 90%, n = 25 B. 99%, n = 50 C. 80%, n = 20 D. 95%, n = 25 E. 98%, n = 50 Answer: D
3) At 90% confidence level, the critical value is z0.05 = 1.645
Margin of error = 6/2
b) We know that if the sample size decreases and the confidence level increases, then the width of the interval becomes wider.
So for a smaller sample size and greater confidence level, the confidence interval will become largest.
So, Option - D is correct.