1 A class survey in a large class for firstyear college stud

1.

A class survey in a large class for first-year college students asked, \"About how many minutes do you study on a typical weeknight?\" The mean response of the 463 students was x = 118 minutes.
Suppose that we know that the study time follows a Normal distribution with standard deviation ? = 65 minutes in the population of all first-year students at this university.

Solution

(A) Given a=1-0.99 = 0.01, Z(0.005) = 2.58 (from standard normal table)

So the lower bound is

xbar - Z*s/vn =118 -2.58*65/sqrt(463) =110.2063

So the upper boudn is

xbar + Z*s/vn =118 +2.58*65/sqrt(463) =125.7937

Answer: C. 110.22 to 125.78

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(B) Answer: B.Normal distribution.