Question

For problems 9, 10, 11, and 12, solve the problems by answering a) State the claim (use a sentence, b) Ho , H1 , and place the claim. c) Test statistic, show and label the formula you use. d) Critical value(s), e) Conclusion and final statement.

An industrial company claims that the mean pH level of the water in a nearby river is 6.8. You randomly select 19 water samples and measure the pH of each. The sample mean and standard deviation are 6.7 and 0.24 respectively. Use α =0.05. Assume the population is normally distributed

Answer 1

a)

Claim: Mean PH level is 6.8

b)

H0: $\mu$ = 6.8

Ha: $\mu$ $\neq$ 6.8

c)

Test statistics

t = $\bar{x}$ - $\mu$ / S / sqrt(n)

= 6.7 - 6.8 / 0.24 / sqrt(19)

= -1.82

This is test statistics value/

d)

Critical value at 0.05 level with 18 df = -2.101 , 2.101

e)

Since test statistics falls in non rejection region that is falls between -2.101 and 2.101, we do not have

sufficient evidence to reject H0.

We conclude that we fail to support the claim at level.