A lift has the capacity of 18 adults or 30 children

A lift has the capacity of 18 adults or 30 children. How many children can board the lift with 12 adults?

  1. 6
  2. 10
  3. 12
  4. 15

Answer

Let the capacity of lift be 90x (LCM of 18 and 30).

Capacity of 1 adult = 90x/18 = 5x

Capacity of 1 child = 90x/30 = 3x

With 12 adults, lift is already occupied with 12 × 5x capacity = 60x capacity.

Remaining capacity = 90x - 60x = 30x

Number of children that can board = 30x/3x = 10 

The correct option is B.