A toy manufacturer wants to know how many new toys children buy each year. A sample of 1417 children was taken to study their purchasing habits. Construct the 99% confidence interval for the mean number of toys purchased each year if the sample mean was found to be 7.7. Assume that the population standard deviation is 1.8. Round your answers to one decimal place.

The 99% confidence interval for the mean number of toys purchased each year is between 7.6 toys and 7.8 toys.

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 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 7.7 - 0.1 = 7.6 toys

The upper end of the interval is the sample mean added to M. So it is 7.7 + 0.1 = 7.8 toys

The 99% confidence interval for the mean number of toys purchased each year is between 7.6 toys and 7.8 toys.

answer: do you still need this?

c) yes, because of asa or aas