Suppose the students construct a 95% confidence interval for the true weight of their rocks. Whose interval do you expect to be more precise (narrower)? (i) The student who weighed the rock 20 times. (ii) The student who weighed the rock 5 times. (iii) Both intervals would be equally precise.

(i) The student who weighed the rock 20 times.

Step-by-step explanation:

The margin of error of a confidence interval is:

In which z is related to the confidence level, is the standard deviation of the population and n is the size of the sample.

From the equation above, the larger the size of the sample, the lower the margin is, that is, the narrower the interval is.

In this question:

A student weighed the rock 20 times and other the 5. From above, the one who weighed the rock 20 times will have the more precise interval.

So the correct answer is:

(i) The student who weighed the rock 20 times.

0.0076, if you meant 4.125 divided by 0.03125 it would be 132

step-by-step explanation:

first you have to move the decimal in 0.03125 over until its behind the 5 which is 5 places over. now the number is 3125

then you have to move the decimal in 4.125, 5 places over. now the number is 4,112,500.

now you divide like you would normally would and get 0.0076