Brett's music teacher spent $134.30 on 17 song books. What is the cost per book?
1 answer:
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Answer:
The confidence interval for the mean is given by the following formula:
(1)
And for this case the 95% confidence interval is given by (2.13; 2.37)
We have a point of estimate for the sample mean with this formula:
And for the margin of error we have the following estimation:
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
represent the sample mean
population mean (variable of interest)
s represent the sample standard deviation
n represent the sample size
Solution to the problem
The confidence interval for the mean is given by the following formula:
(1)
And for this case the 95% confidence interval is given by (2.13; 2.37)
We have a point of estimate for the sample mean with this formula:
And for the margin of error we have the following estimation:
Answer:
Option E: 24.
Step-by-step explanation:
When Caleb (C) has 20 more books than Danica (D), we have:
(1)
Now, when Caleb gives Danica half of his books:
(2)
Danica will have 4 more books than Caleb, so:
(3)
Also we have that:
(4)
By entering equation (2) and equation (3) into equation (4) we have:
(5)
From (1) we have:
(6)
By entering (6) into (5):
And, from (6):
Therefore, the correct option is E, Caleb had to start with 24 books.
I hope it helps you!