Question

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 6.6 parts/million (ppm). A researcher believes that the current ozone level is at an excess level. The mean of 14 samples is 6.7 ppm with a standard deviation of 1.1. Does the data support the claim at the 0.05 level? Assume the population distribution is approximately normal. Step 1 of 5 : State the null and alternative hypotheses.

Answer 1

Solution :

Given that,

Population mean = = 6.6

Sample mean = = 6.7

Sample standard deviation = s = 1.1

Sample size = n = 14

Level of significance = = 0.05

This is a two tailed test.

The null and alternative hypothesis is,

Ho: 6.6

Ha: 6.6

The test statistics,

t = ( - )/ (s/)

= ( 6.7 - 6.6 ) / ( 1.1 / 14)

= 0.34

p-value = 0.7392 ( using t distribution probability table)

The p-value is p = 0.7392 > 0.05, it is concluded that the null hypothesis is fail to reject.

Conclusion :

It is concluded that the null hypothesis Ho is fail to reject. Therefore, there is not enough evidence to claim that the level of

ozone normally found is 6.6 parts/million (ppm) at 0.05 significance level.