Question

The expenditure of a family is directly proportional to the number of members in the family. If the expenditure of a family is ₹ 10,000 when there are 5 members, then find the expenditure when there are 10 members in the family.

• A. ₹ 20,000
• B. ₹ 10,000
• C. ₹ 30,000
• D. ₹ 15,000

Answer 1

The correct option is A ₹ 20,000

Given, the expenditure of a family (E) is directly proportional to the number of members (N) in the family.
$\Rightarrow E\propto N$
Let the constant of variation be k.
$\Rightarrow E=kN$
Given, at E = ₹ 10,000, N = 5.
$So,k=\frac{E}{N}=\frac{10,000}{5}=2,000.$
Hence, the expenditure when there are 10 members in the family (i.e N = 10) = kN = (2000)(10) = ₹ 20,000.