y is inversely proportional to x and y = 4 when x = 1/2. Find x when y = 10.
A
2
B
10
C
1/5
D
1/10
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
y ∝ 1/x
y = K/x
K = xy
K = (1/2) * 4 ( when y = 4 and x = 1/2)
K = 2
∴y = 2/x
10 = 2/x (when y = 10)
10x = 2
x = 2/10
x = 1/5
Source: Myschool Past Questions Archive (Record #8199)