Delhi Police Constable Exam Model Paper 8

Ratio between cost price and marked price of an article = 4 : 5
Formula:
SP = MP × (100 - Discount%) / 100
Calculation:
Ratio between cost price and marked price of an article = 400x : 500x
CP $=400\mathit{x}$ and MP = 500x
SP $=500\mathit{x}\times \left(\frac{90}{100}\right)\times \left(\frac{90}{100}\right)=\mathit{R}\mathit{s}.405\mathit{x}$
Profit $=405\mathit{x}-400\mathit{x}=5\mathit{x}$
∴ Profit % $=\left(5\frac{\mathit{x}}{400}\mathit{x}\right)\times 100=1.25\%$