The strength of ones immune system can be evaluated in sever

The strength of one\'s immune system can be evaluated in several ways. One of the most popular methods involves measuring the concentration of adenosine triphosphate (ATP) in the blood. In women, the mean blood ATP level is 390 ng/mL, and the standard deviation is 115 ng/mL. It has been hypothesized that women with Major Depressive Disorder (MDD) have decreased immune function. A recent study found that a random sample of 70 women with MDD had an average blood ATP level of 355 ng/mL. Using a one-sample z test, what is the p-value of this result? (HINT: This involves a one-tailed hypothesis test.)

Solution

This is an easy problem if you have a TI graphing calculator. Go to STAT, then press right twice, then go right to Z- test, and plug in the values, where the weird u thing means the mean of the population (or 390) and the weird o thing is the standard deviation, the x with the hat is the average in the experiement, and the n is the number of people. Since we are testing that the value found is less than the normal result, use the second option and click < the weird u thing.

The p value you should get is:

.0054427