Answer:
The margin of error for her confdence interval is of 0.3757.
Step-by-step explanation:
We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 18 - 1 = 17
99% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 17 degrees of freedom(y-axis) and a confidence level of
. So we have T = 2.8982
The margin of error is:

In which s is the standard deviation of the sample and n is the size of the sample.
Standard deviation of 0.55 meters.
This means that 
What is the margin of error for her 99% confidence interval?



The margin of error for her confdence interval is of 0.3757.
Answer:
Number of high quality version downloads = 880
Step-by-step explanation:
Let,
x be the number of standard version songs downloaded
y be the number of high quality version songs downloaded
According to given statement,
x+y=1600 Eqn 1
2.8x+4.1y=5624 Eqn 2
Multiplying Eqn 1 by 2.8 to eliminate x
2.8(x+y=1600)
2.8x+2.8y=4480 Eqn 3
Subtracting Eqn 3 from Eqn 2
(2.8x+4.1y)-(2.8x+2.8y)=5624-4480
2.8x+4.1y-2.8x-2.8y=1144
1.3y=1144
Dividing both sides by 1.3

Hence,
Number of high quality version downloads = 880
The ANSWERRRRRRR would be 32