Testing of Parametric Statistical Hypothesis

A scientist for a company that manufactures fabric wants to assess the percentage of polyester in the fabric.

The advertised percentage is 15%. The scientist measures the percentage of polyester in 20 random samples.

Previous measurements found that the population standard deviation is 2.6%.

Sample Id

Percent Polyester

1

15.2

2

12.4

3

15.4

4

16.5

5

15.9

6

17.1

7

16.9

8

14.3

9

19.1

10

18.2

11

18.5

12

16.3

13

20.0

14

19.2

15

12.3

16

12.8

17

17.9

18

16.3

19

18.7

20

16.2

t-Test for Independent samples

The table presents data from two jeans factories. In each of the columns is presented the monthly number of defective products.

The data for factory 1 are for 10 months, and for factory 2 - for 12 months.

Is there a difference in the average number of defective products in the two factories?

Factory 1

Factory 2

80

79

76

73

70

72

80

62

66

76

85

68

79

70

71

86

81

75

76

68


73


66