Equation or expression
2 answers:
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Answer:
We need at least 601 incomes.
Step-by-step explanation:
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
So it is z with a pvalue of , so
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
How many such incomes must be found if we want to be 95% confident that the sample mean is within $500 of the true population mean?
We have to find n, for which . So
Rounding up
We need at least 601 incomes.