What is it you need help with?
Use the midsegment theorem
Answer:
The value of the test statistic is 
Step-by-step explanation:
Our test statistic is:

In which X is the sample mean,
is the expected value,
is the standard deviation and n is the size of the sample.
The level of ozone normally found is 7.5 parts/million (ppm).
This means that 
The mean of 24 samples is 7.8 ppm with a standard deviation of 0.7.
This means that 
Test Statistic:



The value of the test statistic is 
3+1=4
As all parents would teach their babies simple math...take three candies and take one more. How many candies do you have now? Four