Question

A man bought two transistors which cost him Rs. 720. He sold one of them at a loss of 15% and the other at a gain of 19%. If the selling price of both the transistors is same, find the cost price of each.

• A. Rs. $490$ ; Rs. $400$
• B. Rs. $510$ ; Rs. $420$
• C. Rs. $420$ ; Rs. $300$
• D. Rs. $450$ ; Rs. $360$

Answer 1

Answer: (C)

$\Rightarrow$ Let the cost price be $x$ and $y$.

$\Rightarrow$ $x+y=720.$ -------- ( 1 )

$\Rightarrow$ Selling price of one Transistor = $\frac{85x}{100}$ [$\because$ Sold at $15\%$ loss]

$\Rightarrow$ Selling price of other transistor = $\frac{119y}{100}$ [$\because$ Sold at $19\%$ gain]

$\Rightarrow$ $\frac{85x}{100}=\frac{119y}{100}$

$\Rightarrow$ $\frac{x}{y}=\frac{119}{85}$

$\Rightarrow$ $x=1.4y$ ----- ( 2 )

$\Rightarrow$ $1.4y+y=720$ [Substitute ( 2 ) in ( 1 )]

$\Rightarrow$ $2.4y=720$

$\therefore$ $y=Rs.300$

$\Rightarrow$ $x=720-300=Rs.420$

$\therefore$ Cost price of both transistors is $Rs.420$ and $Rs.300.$