Question

Dr. Lopez gives students 90 minutes to complete the final exam for her course. Most students use almost all the

time allowed, and relatively few students finish early, so the distribution of times that it takes students to finish
the exam is strongly skewed to the left. The mean and standard deviation of the finishing times are 85 and 10
minutes, respectively.
Suppose we took random samples of 40 students and calculated as the sample mean finishing time. We can
assume that the students in each sample are independent.
What would be the shape of the sampling distribution of ??
Choose 1 answer:
Skewed to the left
Skewed to the right
No

Answer 1

approximately normal

Explanation:

check conditions for constructing a confidence interval about a proportion:

- random sample or randomized experiment?

- 10 % when sampling without replacement, check n≤1/10N (40 students is enough to assume 10%)

- large count

all conditions are met so it is safe to assume distribution will be approximately normal

Answer 2

Approximatly normal

Explanation: