The ratio 20 minutes to an hour can be written in the form1:n

n = 3

Step-by-step explanation:

To go from 20 to 1, you must divide 20 by 20. So, to find n, you must divide 60 by 20

A sample of 595 should be obtained.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of , we have the following confidence interval of proportions.

In which

z is the zscore that has a pvalue of .

The margin of error is:

Estimate of 0.55

This means that

95% confidence level

So , z is the value of Z that has a pvalue of , so .

What sample size should be obtained if she wishes the estimate to be within a margin of error of 0.04?

This is n for which M = 0.04. So

Rounding up,

A sample of 595 should be obtained.