Question

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 5.7 parts/million (ppm). A researcher believes that the current ozone level is not at a normal level. The mean of 16 samples is 5.4 ppm with a standard deviation of 0.6. Assume the population is normally distributed. A level of significance of 0.02 will be used. Make the decision to reject or fail to reject the null hypothesis.

Answer 1

We have to test whether the current ozone level is at a normal level or not. So,it is a two tailed hypothesis

Population standard deviation is known and sample size is less than 30, so we will use t distribution

Sample size n = 16

sample mean xbar = 5.4

standard deviation s = 0.6

population mean (mu) = 5.7

test statistic =

degree of freedom = n-1 = 16-1 = 15

using t table for t statistic (-2.00) with df(15), we get

p value = 0.0639

p value is greater than 0.02 significance level, failed to reject Ho because result is insignificant