The terms of subtraction are called minuend and subtrahend
Answer:
So the value of the test statistic is -0.85.
Step-by-step explanation:
We know that a sample of 1800 computer chips revealed that 53% of the chips do not fail in the first 1000 hours of their use. The company's promotional literature states that 54% of the chips do not fail in the first 1000 hours of their use.
We get that:

We calculate the standar deviation:

We calculate the value of the test statistic:

So the value of the test statistic is -0.85.
Step-by-step explanation:
Step 1: Substitute 8 in the equation.
Step 2: Minus 8 from 15.
As your testing H0:p=0.79, then you have a two-tailed test.
The p-value at two-tailed test is given by:

Then, you need to check into the standard normal cumulative table to find at which -z you do have a probability of 0.395. Thus:
As you can see in the picture at z=-0.26 you have a P(Z<=-z)=0.3974
And at z=-0.27 you have a P(Z<=-z)=0.3936.
The average of these values is:

Then, you have a probability of 0.395 at a z of:

Then -z=-0.27, thus z=0.27