We need to find out how many adults must the brand manager survey in order to be 90% confident that his estimate is within five percentage points of the true population percentage.
From the given data we know that our confidence level is 90%. From Standard Normal Table we know that the critical level at 90% confidence level is 1.645. In other words,
.
We also know that E=5% or E=0.05
Also, since,
is not given, we will assume that
=0.5. This is because, the formula that we use will have
in the expression and that will be maximum only when
=0.5. (For any other value of
, we will get a value less than 0.25. For example if,
is 0.4, then
and thus,
.).
We will now use the formula

We will now substitute all the data that we have and we will get



which can approximated to n=271.
So, the brand manager needs a sample size of 271
Answer:
B
Step-by-step explanation:
Standard deviation is the average distance away from the mean, thus B is correct
Total pages=125
Pages read in 1 day=12
Pages read in 4 days=4×12=48
Left pages to read=125-48=77 pages
Answer: $257 per month
Explanation:
Pay = monthly payment
Set the total cost equal to number of months times payment per month (which you would leave as a variable because that’s what you’re solving for).
4,626 = 18P
Divide both sides by 18 because you’re trying to isolate the P.
4,626 = 18P —-> 257 = Pr
This leaves you with an evenly split number of 257.