An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an estimate at the 95% level of confidence. For a sample of 582 third graders, the mean words per minute read was 24.1. Assume a population standard deviation of 3.7. Construct the confidence interval for the mean number of words a third grader can read per minute.

The 95% confidence interval for the mean number of words a third grader can read per minute is (23.8, 24.4).

Step-by-step explanation:

We have 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 Z-table as such z has a p-value of .

That is z with a p-value of , so Z = 1.96.

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.

The lower end of the interval is the sample mean subtracted by M. So it is 24.1 - 0.3 = 23.8

The upper end of the interval is the sample mean added to M. So it is 24.1 + 0.3 = 24.4.

The 95% confidence interval for the mean number of words a third grader can read per minute is (23.8, 24.4).

answer: the value should be used for i in the formula of calculation the monthly payment , the interest rate per period is 0.85.

step-by-step explanation:

the given rate of interest i= 85%

in calculating the monthly payment for a loan with an interest rate compounded monthly, the value of the interest rate per period we use in the formula must be in decimal form.

to convert it in decimal, we divide it by 100, we get

hence, the value should be used for i in the formula of calculation the monthly payment , the interest rate per period is 0.85.