Answer:
b. quadruple the sample size.
Step-by-step explanation:
Given that a 95% confidence is given by (15,20) .
this implies that mean = average of lower and higher bounds of confidence interval = 
Margin of error = Upper bound - Mean = 
Confidence level = 95%
Critical value = 1.96
Std error = 
Std devition = Std error * sqrt n = 6.3775
If we want to reduce margin of error by half we must get margin of error as 1.25
For that std error for same critical value = 0.63775
Std deviation did not change
So sample size only changed which implies that sample size is 4 times the original
b. quadruple the sample size.


<h2><u>refer </u><u>to</u><u> the</u><u> attachment</u><u> for</u><u> explanation</u></h2>
<h2><u>hope</u><u> it</u><u> helps</u></h2>
A; the coordinates in that point make M equidistant from H and F.
We have two points so we can find the gradient using y1-y2/x1-x2
gradient = 21-27/2-8
= 1
we know the form for any linear equation is y = mx + c
we have m and a point so we can substitute in point (2,21) to find c
21 = 1 x 2 + c
c = 19
therefore, the equation is y = x + 19