(a) 34 copies
4520 = 1800 + 80c
2720 = 80c
34 = c
(b) $3,720
P = 1800 + 80(24)
P = 1800 + 1920
P = 3720
Let me know if you have questions about this
Answer:

And replacing we got:

And then the estimator for the standard error is given by:

Step-by-step explanation:
For this case we have the following dataset given:
20.05, 20.56, 20.72, and 20.43
We can assume that the distribution for the sample mean is given by:

And the standard error for this case would be:

And we can estimate the deviation with the sample deviation:

And replacing we got:

And then the estimator for the standard error is given by:

Well it seems if you round you would get 1.81 try it
Answer:
Option C is correct.
Step-by-step explanation:
The given data would be most appropriately displayed by a box-and-whisker plot.
a box-and-whisker plot will represent it by representing in form of rectangle with second and third quartile
And in box and whisker plot
The vertical line will represent the median.
Therefore, option C is correct.