T varies inversely as the cube of R. When R = 3, T = (frac{2}{81}), find T when R = 2
-
A.
(frac{1}{18}) -
B.
(frac{1}{12}) -
C.
(frac{1}{24}) -
D.
(frac{1}{6})
Correct Answer: Option B
Explanation
T (alpha frac{1}{R^3})
T = (frac{k}{R^3})
k = TR3
= (frac{2}{81}) x 33
= (frac{2}{81}) x 27
dividing 81 by 27
k = (frac{2}{2})
therefore, T = (frac{2}{3}) x (frac{1}{R^3})
When R = 2
T = (frac{2}{3}) x (frac{1}{2^3}) = (frac{2}{3}) x (frac{1}{8})
= (frac{1}{12})