21) If a92%Confidence Interval for the Population Mean is(67.8,78.9), find its Margin of Error.

A.73.35

B.11.10

C.5.55

D.none

22) According to a survey, 66% of all students in the U. S. own a laptop. For a simple random sample of size 49, construct a 94% Confidence Interval estimate of the Population Proportion p.

A.(0.5548, 0.7652)

B.(0.5328, 0.7872)

C.(0.5018, 0.8182)

D.none

23) Suppose that the number of students passed a Statistics class are normally distributed. A simple random sample of size 33 students has the standard deviation of 5 students was selected. Construct a 95% Confidence Interval estimate for the population standard deviation of the numbers of students passed in all such Statistics classes.

A.(3.67, 5.72)

B.(4.13, 6.90)

C.(4.28, 6.58)

D.(3.79, 5.49)