1) The formula used for determining the confidence interval is
Sample mean +/- Critical value (or z-score corresponding to 90% confidence) * Standard
error of mean
8439 +/- 1.645 * 100/sqrt 25
8439 +/- 1.645 * 20
8439 +/- 32.9
2) The only difference in this case is finding the critical value i.e., z-score corresponding to 92% confidence which is 1.75 approximately
Then the confidence interval is
8439 +/- 1.75 * 100/sqrt 25
8439 +/- 1.75 * 20
8439 +/- 35
Lower limit is 8439 - 35 = 8404
The upper limit is 8439 + 35 = 8474
Answer:
v = 13.5 m/s is the answer
mark me as brainliest if u found it helpful
