Question

Total cost of 100 pens is Rs. 500. If cost of each pen is decreased by 20% and number of pens is increased by 50%, total cost is increased by (In Rs.)
1. 200
2. 150
3. 100
4. None of these

Answer 1

Correct Answer - Option 3 : 100

Given:

Total cost of 100 pens = 500

Cost of each pen is decreased by = 20%

Number of pens is increased by = 50%

Formula used:

If a quantity (x) is increased or decreased by a%, then final value of the quantity = (100 ± a) % of x, where ± shows the increment / decrement.

Total cost of 100 pens = 500

∴ cost of 1 pen = 500 / 100 = 5

Now, cost of 1 pen = (100 – 20) % of 5 = 80% of 5 = 4

Number of pens = (100 + 50) % of 100 = 150% of 100 = 150

∴ total cost of 150 pens = 150 × 4 = 600

Therefore, total cost of pens is increased by 600 – 500 = Rs. 100