Suppose the test scores of 75 students in a class follows normal distribution with a standard deviation of 3. The sample mean is 68.

What distribution is used in constructing confidence intervals in this problem?

t-distribution

z-distribution

geometric

binomial

What is Maximal Margin of Error (E) at 95% confidence?

0.0784

0.0658

0.56984

0.67896

Construct a 95% confidence interval

(-0.56984, 0.56984)

(67.32101,68.67896)

(65,71)

(-0.67896, 0.67896)