Question

A person purchases $90$ clocks and sells $40$ clocks at a gain of $10\%$ and $50$ clocks at a gain of $20\%$. If he sold all of them at a uniform profit of $15\%$, then he would have got $\text{Rs.}40$ less. The cost price of each clock is

• A. $\text{Rs.}50$
• B. $\text{Rs.}60$
• C. $\text{Rs.}80$
• D. $\text{Rs.}90$

Answer 1

Answer: (C)

Let the $C.P$ of each clock be $\text{Rs.}x.$

Then $C.P$ of $90$ clocks $=\text{Rs.}90x.$

By using the given information,

$(\frac{110}{100}\times 40x)+(\frac{120}{100}\times 50x)-(\frac{115}{100}\times 90x)=40$

$\Rightarrow 44x+60x-103.5x=40$

$\Rightarrow 0.5x=40$

$\Rightarrow x=80$

So, the $C.P$ of each clock is equal to $\text{Rs.}80.$