Answer:
a. no the graph fails the vertical line test
Using the t-distribution to build the 99% confidence interval, it is found that:
- The margin of error is of 3.64.
- The 99% confidence interval for the population mean is (19.36, 26.64).
<h3>What is a t-distribution confidence interval?</h3>
The confidence interval is:

In which:
is the sample mean.
- s is the standard deviation for the sample.
The critical value, using a t-distribution calculator, for a two-tailed 95% confidence interval, with 21 - 1 = 20 df, is t = 2.086.
The other parameters are given as follows:

The margin of error is given by:

Hence the bounds of the interval are:


The 99% confidence interval for the population mean is (19.36, 26.64).
More can be learned about the t-distribution at brainly.com/question/16162795
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Let the total earnings be = x
Jennifer and Chris split the earnings in the ratio 3:2
Jennifer earned = $48


x=80
Hence total earnings are $80
(a) Chris earning is = 
Hence, Chris earns $32
(b) Jennifer spends 30% of her earnings on a book.
So, price of the book = 
Price of book = $14.40
(c) Jennifer also buys a magazine for = $5.40
So, total money Jennifer spent on book and magazine = 14.40+5.40=19.80
Money left with Jennifer = 48-19.80= $28.20
In fractions =
or multiplying the numerator and denominator by 10, we get
=
(d) Let the original price of the shirt = x
reduction percentage on x= 40%
Price paid after reduction = 16.80



Hence, the original price of the shirt was $42.
It could be any number that is 4 and under