W is directly proportional to U. If W = 5 when U = 3, find U when W = 2/7
A
6/35
B
10/21
C
21/10
D
35/6
Verified Correct Answer: A.
Step-by-Step Mathematical Solution
W ∝ U
W = KU
K = \(\frac{W}{U}\)
K = \(\frac{5}{3}\)
W = \(\frac{5}{3}U\)
\(\frac{2}{7} = \frac{5}{3}\)U
U = \(\frac{2}{7} \times \frac{3}{5}\)
U = \(\frac{6}{35}\)
Source: Myschool Past Questions Archive (Record #9317)