Delhi Police Constable Exam Model Paper 4

Tips & Tricks
GIVEN:2 successive discounts of 25% and 40%
CALCULATION:
Single effective discount = $\left[1-\left(1-0.25\right)\times \left(1-0.4\right)\right]\times 100$
⇒ $\left[1-0.75\times 0.6\right]\times 100$
⇒ $\left[1-0.45\right]\times 100$
⇒ $0.55\times 100$
⇒ 55%
∴ Single effective discount is 55%
Smart Trick
Effective discount for a% and b% discounts = (a + b - ab/100)
So,
Effective discount for 25% and 40% discounts = $25+40-\frac{1000}{100}=55\%$