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:

0.4 because if it’s five or more, add one more. If it’s four or less, let it rest.
The diameter is 24 since if you ÷ it by 2 you get 12 to get area it is radius squared so 12 × 12= 144×pi which is 3.14= 452.16 mm you can even check in a calculator
> is greater than
< is less than
¾ an hour is 45 minutes
So to have your answers you need to do a cross product :
45 minutes —> 2/3 of a chapter
60 minutes —> X of a chapter
((2/3) • 60) / 45
40/45 = 8/9
Answer : You read 8/9 of a chaper per hour! :)