Question

Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 5.5 parts/million (ppm). A researcher believes that the current ozone level is not at a normal level. The mean of 9 samples is 5.1 ppm with a standard deviation of 0.8. Assume the population is normally distributed. A level of significance of 0.05 will be used. Find the value of the test statistic. Round your answer to three decimal places.

Answer 1

Solution :

Given that,

Population mean = = 5.5

Sample mean = = 5.1

Sample standard deviation = s = 0.8

Sample size = n = 9

Level of significance = = 0.05

This is a two tailed test.

The null and alternative hypothesis is,

Ho: 5.5

Ha: 5.5

The test statistics,

t = ( - )/ (s/)

= ( 5.1 - 5.5 ) / ( 0.8 /9)

= -1.500

The test statistic is -1.500