A shopkeeper buys 100 pens for 200 and sells20 of them at a gain of 10

1.	A shopkeeper buys 100 pens for 200 and sells20 of them at a gain of 10%. At what gain percentmust he sell the remainder so as to gain 20% in all?
Answer» Cost price of 100 pens = Rs. 200 Gain % = (SP - CP)100/CP Gain of 20% in all Total SP = CP + (CP Gain%)/100 ∴Total SP= 200 +(20020)/100 = Rs.240 Cost price of 20 pens = (200/100)20 = Rs.40 S.P of 20 pens at a gain of 10% = 40 + (40 × 10)/100 = Rs.44 S.P of balance 80 pens = Total SP - SP of 20 pens = 240 - 44 = Rs.196 C.P of 80 pens = 200*80/100 = Rs.160 Required gain % = (196 -160)×100/160 = 3600/160 = 22.5% ∴ He has to sell the balance pens at a gain of 22.5%.

A shopkeeper buys 100 pens for 200 and sells20 of them at a gain of 10%. At what gain percentmust he sell the remainder so as to gain 20% in all?

Answer»

Cost price of 100 pens = Rs. 200

Gain % = (SP - CP)*100/CP

Gain of 20% in all Total SP = CP + (CP * Gain%)/100

∴Total SP= 200 +(200*20)/100 = Rs.240

Cost price of 20 pens = (200/100)*20 = Rs.40

S.P of 20 pens at a gain of 10% = 40 + (40 × 10)/100 = Rs.44

S.P of balance 80 pens = Total SP - SP of 20 pens = 240 - 44 = Rs.196

C.P of 80 pens = 200*80/100 = Rs.160

Required gain % = (196 -160)×100/160 = 3600/160 = 22.5%

∴ He has to sell the balance pens at a gain of 22.5%.