Hello there! So, the item has a 20% discount, but Juan still had to pay 80% for the item. To find the amount he paid, all you have to do is multiply the price by the percentage. We multiply by 80%, because he still had to pay the portion of the price. 80 * 80% (0.8) is 64. The. Juan paid $64.
Are you looking for y and if so y=80
Using the z-distribution, as we have the standard deviation for the population, it is found that the smallest sample size required to obtain the desired margin of error is of 77.
<h3>What is a z-distribution confidence interval?</h3>
The confidence interval is:

In which:
is the sample mean.
is the standard deviation for the population.
The margin of error is given by:

In this problem, we have that the parameters are given as follows:
.
Hence, solving for n, we find the sample size.






Rounding up, the smallest sample size required to obtain the desired margin of error is of 77.
More can be learned about the z-distribution at brainly.com/question/25890103