Suppose that the population of the scores of all high school seniors who took the SAT
Math (SAT-M) test this year follows a Normal distribution with standard deviation
σ = 100. You read a report that says, “On the basis of a simple random sample of 100
high school seniors that took the SAT-M test this year, a confidence interval for μ is
found to be 512.00 ± 25.76.” What was the confidence level used to calculate this

Your company is producing special battery packs for the most popular toy during the holiday
season. The life span of the battery pack is known to be Normally distributed with a mean of 250
hours and a standard deviation of 20 hours.
11. What percentage of battery packs lasts longer than 260 hours?
12. If a simple random sample of four battery packs is selected from your company and we
assume that their life spans are independent, what is the probability that they all last
longer than 260 hours?
13. If a simple random sample of four battery packs is selected from your company, what is
the probability that the average lifetime of these four packs is longer than 260 hours?
14. Determine whether each of the following statements is true or false.
A) The margin of error for a 95% confidence interval for the mean μ increases as the
sample size increases.
B) The margin of error for a confidence interval for the mean μ, based on a specified
sample size n, increases as the confidence level decreases.
C) The margin of error for a 95% confidence interval for the mean μ decreases as the
population standard deviation decreases.
D) The sample size required to obtain a confidence interval of specified margin of
error m increases as the confidence level increases.

Please refer to this announcement

Do not simply retype or paste a question from your book or study material

We won't do your homework questions for you.
You were given the assignment for you to learn.

If you come up with your own answer and post it for us to critique that is within reason.

If you have some SPECIFIC questions that you couldn't find or didn't understand, we may help with that.
But this is your assignment, so show us you have at least attempted to complete it on your own.