$36. You have to add the two together to get your answer. Grab a calculator and this will be easier :)
The answer is A.Because the picture shows.
Using the z-distribution, it is found that a sample of 171 should be selected.
<h3>What is a z-distribution confidence interval?</h3>
The confidence interval is:

The margin of error is:

In which:
is the sample mean.
is the standard deviation for the population.
For this problem, the parameters are:

Hence we solve for n to find the needed sample size.





n = 170.7.
Rounding up, a sample of 171 should be selected.
More can be learned about the z-distribution at brainly.com/question/25890103
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By dividing each general term by 3.
Example:
(3/3=1)
In this question, you're trying to find the unit rate in which the teacher can grade tests.
A unit rate is another word for "rate of change".
This means that we have to find how many tests the teacher could grade in 1 minute.
To find the unit rate, divide 18 by 15
18 ÷ 15 = 1.2
This means that Mr. Rivera can grade 1.2 tests in 1 minute.
Answer:
1.2 tests