Page 62 - Basic Statistics

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The critical value : Z-table = z  2 / = 2.58 (from Z-tables)

Test results : z > z  2 / , ie 2.69 > 2.58 . Furthermore, H is rejected at the 1
0
percent significance level. It was concluded that the average battery life is not

the same as 55 hours.

b). Test hypothesis: H :  = 55;
0
0
H :  < 55
1
0

Significance level:  = 0.01

Z-table = z = 2.33 ( from tables )


Test results: z < -z , ie -2.69 < -2.33 . Furthermore, H is rejected at the 1

0
percent significance level. It was concluded that the average battery life of less

than 55 hours.

Worked Example 4.3:

The results of the last survey of the labor force states that in one year, the
average number of days each employee absent due to illness was 15 days. A

researcher using a random sample of 25 workers, and noted the absence of each

worker in one year is as follows.

5 25 10 0 3 50 12 14 40

12 32 8 4 47 20 14 16 10
1 22 58 5 23 18 9

Perform hypothesis testing at 5 percent significance level that

a. Average worker absent in a year of 15 days

b. Average worker absences greater than 15 days.

~~* CHAPTER 4 HYPOTHESIS TESTING *~~