Answer:
And rounded up we have that n=421
Step-by-step explanation:
We know that the sample proportion have the following distribution:

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by
and
. And the critical value would be given by:
The margin of error for the proportion interval is given by this formula:
(a)
And on this case we have that
and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
We assume that a prior estimation for p would be
since we don't have any other info provided. And replacing into equation (b) the values from part a we got:
And rounded up we have that n=421
Answer:
4800 dollars
Step-by-step explanation:
4000 multiply 0.2=800
4000+800=4800
Answer:
7
Step-by-step explanation:
2n + 4n = 6n, adding like terms
6n = 42
6n/6 = 42/6
n = 7