A watch is sold at a profit of 20%. If both the cost price and the selling price of the watch are decreased by Rs. 100, the profit would be 5% more. Original cost price of the watch is -
A. Rs. 450
B. Rs. 500
C. Rs. 550
D. Rs. 600
Answer: Option B
Solution(By Examveda Team)
$$\eqalign{ & {\text{Let C}}{\text{.P}}{\text{. be Rs}}{\text{. }}x \cr & {\text{Profit}} = 20\% \cr & {\text{S}}{\text{.P}}{\text{.}} = 120\% {\text{ of Rs}}{\text{. }}x \cr & \,\,\,\,\,\,\,\,\,\,\,\, = {\text{Rs}}{\text{.}}\frac{{6x}}{5} \cr & {\text{New C}}{\text{.P}}{\text{.}} = {\text{Rs}}.\left( {x - 100} \right) \cr & {\text{New S}}{\text{.P}}{\text{.}} = {\text{Rs}}.\left( {\frac{{6x}}{5} - 100} \right) \cr} $$$$\eqalign{ & {\text{Profit = }} \cr & {\text{Rs}}.\left[ {\left( {\frac{{6x}}{5} - 100} \right) - \left( {x - 100} \right)} \right] \cr & = {\text{Rs}}.\frac{x}{5} \cr & \therefore \frac{x}{5} \times \frac{1}{{\left( {x - 100} \right)}} \times 100 = 25 \cr & \Rightarrow 20x = 25\left( {x - 100} \right) \cr & \Rightarrow 5x = 2500 \cr & \Rightarrow x = 500 \cr} $$
Related Questions on Profit and Loss
A. 45 : 56
B. 45 : 51
C. 47 : 56
D. 47 : 51
A. Rs. 2600
B. Rs. 2700
C. Rs. 2800
D. Rs. 3000
A. A neither losses nor gains
B. A makes a profit of 11%
C. A makes a profit of 20%
D. B loses 20%
A. Rs. 3,750
B. Rs. 3,250
C. Rs. 2,750
D. Rs. 2,250
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