Answer:
A sample of 18 is required.
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 Z-table as such z has a p-value of
.
That is z with a pvalue of
, so Z = 1.88.
Now, find the margin of error M as such
In which
is the standard deviation of the population and n is the size of the sample.
A previous study indicated that the standard deviation was 2.2 days.
This means that 
How large a sample must be selected if the company wants to be 92% confident that the true mean differs from the sample mean by no more than 1 day?
This is n for which M = 1. So



Rounding up:
A sample of 18 is required.
Answer:
A is 10 dollar cheaper than B
Step-by-step explanation:
A : 40 dollars plus 45*2=90
90+40= 130 dollars
B:100 dollars 45*1=45
100+45= 145 dollars
Answer:A?
Step-by-step explanation:
It's an 11% increase. To find this, you have to subtract 85 from 94.35 and then you divide that difference by the original amount. In this case it's 85. After that, you get .11. Then you just turn it into a percent.