Question

A shopkeeper sells one transistor for Rs. 840 at a gain of 20% and another for Rs. 960 at a loss of 4%. His total gain or loss percent is:

Answer 1

C.P. of 1st transistor = Rs.100 x 840= Rs. 700.
                                             120
C.P. of 2nd transistor = Rs. 100 x 960 = Rs. 1000
                                               96

So, total C.P. = Rs. (700 + 1000) = Rs. 1700.

Total S.P. = Rs. (840 + 960) = Rs. 1800.

Gain % =100x 100%=10000
                1700               1700

Answer 2

CP of first transistor = [(100/100+gain%)×SP]

→ = [100/(100+20)×840]

→ = (100/120×840)

→ = ₹700

CP of second transistor= [(100/100-loss%)×SP]

→ = [(100/100-4)×960]

→ = [(100/96)×960]

→ = ₹1000

Total CP = ₹700+₹1000 = ₹1700

Total SP = ₹840+₹960 = ₹1800

Gain = ₹1800 - ₹1700 = 100

Gain % = [(gain × 100)/CP]%

= (100×100/1700)%

=100/17%

Hope it helps