Correct Answer - Option 1 : 27
Given:
With the money, he buys = 50 pens or 150 pencil
by keeping 10% aside, with the rest of the money he buys = 54 pencils and n pen
Calculation:
Let the cost of each pen be x and each pencil be y
Then, total money = 50 × x = 150 × y
Ratio of rate of one pen to pencil = x ∶ y = 3 ∶ 1
Amount spent after keeping aside money = 54y + xn
54y + xn = 90% of 50x or 90% of 150y
Applying the values obtained in ratio in the above equation we get,
54 × 1 + 3 × n = (9/10) × 50 × 3
n = (135 - 54) ÷ 3 = 81/3 = 27
∴ n is 27.