Answer:
Step-by-step explanation:
The formula for determining the confidence interval for the difference of two population means is expressed as
Confidence interval = (x1 - x2) ± z√(s²/n1 + s2²/n2)
Where
x1 = mean sale amount for mail order sales = 82.70
x2 = mean sale amount for internet sales = 66.9
s1 = sample standard deviation for mail order sales = 16.25
s2 = sample standard deviation for internet sales = 20.25
n1 = number of mail order sales = 17
n2 = number of internet sales = 10
For a 99% confidence interval, we would determine the z score from the t distribution table because the number of samples are small
Degree of freedom =
(n1 - 1) + (n2 - 1) = (17 - 1) + (10 - 1) = 25
z = 2.787
Margin of error =
z√(s²/n1 + s2²/n2) = 2.787√(16.25²/17 + 20.25²/10) = 20.956190
Answer:
$150
Step-by-step explanation:
I feel like this is a trick question
Answer:
You must survey 784 air passengers.
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 zscore that has a pvalue of 
.
The margin of error is:
95% confidence level
So 
, z is the value of Z that has a pvalue of 
, so 
.
Assume that nothing is known about the percentage of passengers who prefer aisle seats.
This means that 
, which is when the largest sample size will be needed.
Within 3.5 percentage points of the true population percentage.
We have to find n for which M = 0.035. So
You must survey 784 air passengers.
Answer: Marci: 60 minutes
Bobby: 30 minutes
Max: 90 minutes
Step-by-step explanation:
50% of 60 is 30.
100% of 60 is 60, plus 50% is 60+30, which gets you 90.
