89972 is already rounded to 3 significant figures.
x2 =9
x4 =64
64-9 =55
4-2 = 2
55/2 = 27.5
average rate is 27.5, B is the answer
A.
A = 400 (1 + (0.02)/4)^4t where t = number of years and A = amount after t years
simplifying that becomes
A = 400 (1.005)^4t
b amount after 5 years is
400 (1.005)^(4*5) = 400 (1.005)^20 = $ 441.96
We know that the sandbox is square, and that the area is 160 sq ft. Since A = s^2 for a square, let's work backwards and find s if A = 160 sq ft = s^2.
s^2 = 160 = 16(10). We do this because 16 is the largest perfect square factor of 160.
Then the length of one side of the square is approx. s = 4√10 ft (12.65 ft)
Perpendicular slope: opposite and reciprocal
-4 opposite and reciprocal = 1/4
Y = 1/4x + b
Plug in point
-3 = 1/4(8) + b
-3 = 2 + b, b = -5
Solution: y = 1/4x - 5
