What sample size is needed to give a margin of error within in estimating a population mean with 95% confidence, assuming a previous sample had .

The sample size needed is n(if a decimal number, round up to the next integer), considering the estimate of the proportion (if no previous estimate use 0.5) and M is the desired margin of error.

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 z-score that has a p-value of .

The margin of error is of:

95% confidence level

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

Needed sample size:

The needed sample size is n. We have that:

The sample size needed is n(if a decimal number, round up to the next integer), considering the estimate of the proportion (if no previous estimate use 0.5) and M is the desired margin of error.

x=30

step-by-step explanation:

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