Question

If a person sold his watch for Rs. 144 and got a
percentage of profit equal to the cost price, then the
cost price of the watch is
(1) Rs. 80 (2) Rs. 88
(3) Rs. 84 (4) Rs. 83

Answer 1

Answer is 80.

The cost price is 80 and he sold at Rs.144 and his profit is 144-80=64

Answer 2

Answer:

1) Rs. 80

Step-by-step explanation:

It is given that the selling price is Rs. 144. It is also given that the percentage of profit is equal to the cost price.

Let the cost price be x. Therefore, the percentage of profit = x%.

Selling price = x + x*(x/100)

$144=x+\frac{x^2}{100}\\14400=100x+x^2\\x^2+100x-14400=0\\(x + 180)(x - 80)=0\\x=80$