The average weight of a certain number of apples in a basket was 0.5 kg. If 10 apples with an average weight of 0.7 kg are removed from the basket and 5 apples with an average weight of 0.6 kg are added to the basket, then the average weight of the apples in the basket decreases by 0.1 kg. What was the initial number of apples in the basket?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 20.
Let initial apples = x
Initial total weight = 0.5x
After removing: -7 kg (10×0.7), after adding: +3 kg (5×0.6)
New total weight = 0.5x - 4
New apples = x - 5
New average = 0.4 kg
(0.5x - 4) / (x - 5) = 0.4
→ 0.5x - 4 = 0.4x - 2
→ 0.1x = 2
→ x = 20