Answer:
The interest when rate is 5.2% is $48.88
Step-by-step explanation:
if interest (I) varies directly as interest rate (R)
Then
I ∝ R
I=cR
c= constant
if interest is $47 when interest rate is 5%
47 =.05c
c = 940
if interest rate is 5.2% then
I = 940 x .052
=48.88
=$48.88
90 x 7 = 630 square feet total
0.5 fluid ounce per sq ft
630 x 0.5 = 315 fluid ounces are needed