# confidence interval for mean and proportion.

1. In considering the production of a new car accessory, the Michigan Manufacturer Company wants to do a marketing study to determine the proportion of cars with cellular phones. How many cars must be sampled to have 92% confidence that the sample proportion is in error by no more than 0.03? The answer is 851 need help setting up and solving to get this.

2. the data set show 17 weights (in grams) of red M & M's. For the sample, the mean is 0.9043g and the standard deviation is 0.0414g. Construct a 90% confidence interval estimate of the standard deviation of the weights of all red M & M's. answer is 0.0323 < o < 0.0587.

Data 17 weights of red m & m's

0.864

0.952

o.941

0.817

0.957

0.920

0.958

0.933

0.870

0.871

0.921

0.896

0.913

0.844

0.931

0.909

0.876

3.Total weights of garbage discarded by 62 households in one week. For the sample the mean is 27.44lb and the SD is 12.46lb. Construct a 99% confidence interval estimate of standard deviation for the weights of the garbage discarded by all households.

answer is 10.15 < o < 16.33

data set has 37 households in set

42.99

51.90

20.20

36.80

19.02

15.43

20.71

17.01

45.35

49.37

18.06

17.41

23.67

19.13

20.99

21.18

29.06

14.95

4.43

24.82

20.80

25.79

14.62

28.41

27.17

54.47

13.12

45.77

34.79

37.26

51.58

24.81

26.18

11.25

28.15

11.14

11.70

https://brainmass.com/statistics/confidence-interval/confidence-interval-mean-proportion-128455

#### Solution Summary

The solution gives complete steps of construction of confidence interval for mean and proportion.