A researcher conducted a study of the access speed of 45 hard drives and concluded that his maximum error of estimate was 20. if he were to conduct a second study to reduce the maximum error of estimate to 5, about how many hard drives should he include in his new sample?

He should include 720 hard drives in his new sample.

Step-by-step explanation:

Let E be the margin of error and n be the sample size , then 4

Also, by equation of inverse variation , we have

Put  (given) , we get

Taking square on both sides , we get

Hence, he should include 720 hard drives in his new sample.

the least common denominatore of 7 and 2 is 9

step-by-step explanation:

7+2=9