A varies jointly with B and C. A = 6 when B = 3 and C = 2. Find A when B = 5 and C = 7.
Answer & explanation
Correct answer: option 2
When A varies jointly with B and C
A = kBC, where k is a constant
A = 6, B = 3, C = 2
Then, 6 = k.6
⇒ k = 1
Now, when B = 5 and C = 7
A = kBC ⇒ A = 1.5.7
⇒ A = 35