A. but I would double check on that one first.
Y=68+4x
100=68+4x
-68=-68
32=4x
Divide both sides by 4
x=it will take 8 min. for the water to reach 100 degrees
y=total degrees
x=# of minutes
We want to find the value that makes

To find it we must look at the standard normal table, using the complementary cumulative table we find that

Then, using the z-score we can find the minimum score needed, remember that

Where
σ = standard deviation
μ = mean
And in our example, x = minimum score needed, therefore

Rounding to the nearest integer the minimum score needed is 568, if you get 568 you are at the top 20.1%.
Wait are you going to send a picture to fully show us what the question is about
Side = 8m
He increases length by 2m and reduces width by 2m
(a.) New dimensions will be -
Length = 10m and Width = 6m
(b.) Area = length x breadth (or width)
here we will use the special product (x+y) (x-y)
length = (x+y) and width = (x-y)
area = (8+2) x (8-2)
8^(2) - 2^(2)
= 60