Answer:
0.5085
Step-by-step explanation:
Given that an office has 30 computers. Seventeen of the 30 are Macintosh, and the remaining thirteen are windows.
When two computers are randomly selected without replacement
no of ways of selection =
No of ways of selecting one window and one Mac =
Prob that the sample contains exactly one windows machine and exactly one Macintosh=
Answer:
He must survey 123 adults.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of , and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the z-score that has a p-value of .
The margin of error is:
Assume that a recent survey suggests that about 87% of adults have heard of the brand.
This means that
90% confidence level
So , z is the value of Z that has a p-value of
, so
.
How many adults must he survey in order to be 90% confident that his estimate is within five percentage points of the true population percentage?
This is n for which M = 0.05. So
Rounding up:
He must survey 123 adults.