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:
THE ANWSER IS 4
Step-by-step explanation:
Answer:
<h3>t = 15d</h3>
Step-by-step explanation:
You must first know that 1 week = 7days
If Sophie practices the piano 105 minutes in 1 week, this can be expressed as;
105 minutes = 7days
to calculate the total time t that she practices for any number of days, d, we will say;
t minutes = d days.
Solving both expression;
105 minutes = 7days
t minutes = d days.
Cross multiply;
7 * t = 105 * d
7t = 105d
Divide both sides by 7;
7t/7 = 105d/7
t = 15d
Hence a proportional equation for t in terms of d that matches the context is expressed as t = 15d
<span> x= Pi, x = 2pi/3, x = 4pi/3
That is the answer</span>
