Our environment is very sensitive to the amount of ozone in the upper atmosphere. The level of ozone normally found is 6.8 parts/million (ppm). A researcher believes that the current ozone level is at an insufficient level. The mean of 10 samples is 6.4 ppm with a standard deviation of 1.1. Does the data support the claim at the 0.05 level

The test statistics fall in the critical region and hence null hypothesis is to be rejected.

Step-by-step explanation:

The null hypothesis : H0 : Mean = 6.80  

Alternative hypothesis: Ha: Mean is not equal to 6.80

As per the z statistics  

z = (x’-mean)/(sigma/sqrt n)

Substituting the given values, we get –  

z = 6.4-6.8/(1.1/sqrt 10)

z = -1.149

z test statistics is -1.149

Critical value for two tailed test at 98% confidence is .10749

The test statistics fall in the critical region and hence null hypothesis is to be rejected.

40 is the final : )