Question

By selling 130 cassettes, a man gains an amount equal to the selling price of 5 cassettes. Find the gain per cent.

Answer 1

It is given that,
Gain = SP of 5 cassettes .....(1)
Gain = SP of 130 cassettes − CP of 130 cassettes
⇒ SP of 5 cassettes = SP of 130 cassettes − CP of 130 cassettes [From (1)]
⇒ CP of 130 cassettes = SP of 125 cassettes .....(2)
Let the CP of 1 cassettte be ₹x.
∴ CP of 125 cassettes = ₹125x
CP of 130 cassettes = ₹130x
SP of 125 cassettes = CP of 130 cassettes [From (2)]
⇒ SP of 125 cassettes = ₹130x
Now, gain% $=\frac{\mathrm{SP}-\mathrm{CP}}{\mathrm{CP}}\times 100\%=\frac{\left(130x-125x\right)}{125x}\times 100\%$$=\frac{5x}{125x}\times 100\%=4\%$
Thus, the gain percent is 4%.