Question

The random sample shown below was selected from a normal distribution. 8, 10, 6, 4, 5, 3 O Complete parts a and b.

Answer 1

a)

The confidence interval can be calulated using -

-Z F X S Vn 옮

The mean is 6 whereas the standard deviation comes out to be 2.6.

For 95% the Z value is 1.960

6 +- 1.96*[2.6 / (6)**0.5]

6 +- 1.96*[2.6/2.5]

6 +- 1.96*1.064

6 +- 2.08 = 3.91 and 8.08

The 95% confidence interval is (3.91, 8.08).

b)

Increasing the sample size decreases the width of confidence intervals, because it decreases the standard error.

Option A is the right answer.

8 Mean S.D 6 AVERAGE(E6:E11) 2.6 STDEV.S(E6:E11) 10 LD 4 5 3