A researcher is interested in estimating the mean blood alcohol content of people arrested for driving under the influence. Based on past data, the researcher assumes a population standard deviation of 0.065. What sample size is needed to estimate the true mean blood alcohol content within .005 units at the 95% confidence level?

We need a sample size of at least 650

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.

In this problem:

We need a sample of size at least n

n is found when

So

Rounding up

We need a sample size of at least 650

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step-by-step explanation:

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8+10

step-by-step explanation:

you multiply 4 by 2 and 5 by 2