Question

A shopkeeper makes a profit of $20\%$ on selling a transistor radio for $\text{Rs}840$. For how much should he sell another transistor radio, whose cost price is $\text{Rs}25$ more than the first one, to make the same percentage profit ?

• A. $\text{Rs}870$
• B. $\text{Rs}910$
• C. $\text{Rs}960$
• D. $\text{Rs}1010$

Answer 1

Answer: (A)

$\text{Rs}870$

Given, for first transistor
S.P $=$ Rs. $840$
Profit $=20$ $\%$
Now, with this S.P. and for Profit $\%$ $=\frac{\text{S.P.}-\text{C.P.}}{\text{C.P.}}\times 100=20\%$
$\Rightarrow \frac{840-\text{C.P.}}{\text{C.P.}}\times 100=20$
$\Rightarrow 840-\text{C.P.}=0.20\text{C.P.}$
$\Rightarrow 1.20\text{C.P.}=840$
$\Rightarrow \text{C.P.}=$ Rs. $700$
And for another transistor
$\text{C.P}=$ Rs. $700+$ Rs. $25=$ Rs. $725$
Profit $=20$ $\%$
So, Profit $\%$ $=\frac{\text{S.P.}-\text{C.P.}}{\text{C.P.}}\times 100=20$
$=\frac{\text{S.P.}-725.}{725}\times 100=20$
$\Rightarrow \text{S.P.}-725=145$
$\Rightarrow \text{S.P.}=$ Rs. $870$