Sampling – Exercise 4

1) The University of Mars is interested in the average amount per week spent on grocers by married graduate students living in a high-rise apartment complex consisting of 15 floors, each floor having 10 apartments. We take a random sample of n=3 floors and obtain the following data:

Floor 2	Floor 6	Floor 9
$55	$95	$56
75	72	68
65	66	56
52	76	84
60	56	69
72	71	74
85	65	84
69	59	79
57	86	76
70	64	73

a) Obtain an average amount (per week) spent by a graduate student on grocers and its standard error.

b) Obtain an analysis of variance table and unbiased estimates of S², S²_W, S²_B

c) Estimate r.

2) We are interested in a shoe manufacturing company’s shoe defective rate an a certain day. There are 24 production lines and each manufactures 1,000 pairs of shoes per day. We select 3 lines and gather the following data:

Line	2	9	17
#of defective shoes	8	6	7

Obtain an estimate of the defective rate and a 95% confidence interval for it.