Question

By a local policy, any industrial plant cannot discharge more than 500 gallons of waste water into the local lake in any given hour. A researcher randomly sampled 100 hours when the plant is in production, and record the gallons of waste water discharged. Below is the statistical software print out of the summary statistics:

Variable	n	mean	SD
Waste	100	512	50

(2.1) The researcher is interested in whether the plant violated the local policy. State the

null and the alternative hypotheses, and explain your reasoning for choosing an one-sided or a two-sided test.

2.2 Compute the test statistic. Show your work.

2.3 A statistical software finds that the corresponding p-value equals 0.04. At a= 0.01, interpret the result

2.4 Is the result practically significant? Why or why not?

2.5 Increasing from 0.01 to 0.05, how does the probability of Type I error change? How does the probability of Type II error change?

Answer 1

Solution-21.

Ho:

Ha:

one tail t test

Cannot discharge more than 500 gallons of waste given so it should be less than or equal

2.2 Compute the test statistic. Show your work.

t =xbar-mu/s/sqrt(n)

t=(512-500)/(50/sqrt(100))

t=2.4

2.3 A statistical software finds that the corresponding p-value equals 0.04. At a= 0.01, interpret the result

p=0.04

alpha=0.01

P>alpha

Do not reject Ho.

Accept Ho

There is sufficient statisitical evidence at 1% level of significance to conclude that  the plant has not violated the local policy that any industrial plant cannot discharge more than 500 gallons of waste water into the local lake in any given hour

2.4 Is the result practically significant? Why or why not?

Result not practically significant as p>0.01