The price of fuel decreases by 40%, 50% and 15% in three successive months, but increases by 40% in the fourth month. What is the percentage increase/decrease in the price of fuel in the fourth month as compared to its original price?

Correct option is A

Given:

The price of fuel decreases by 40%, 50%, and 15% in three successive months, but increases by 40% in the fourth month. 

Formula Used:

New Price after decrease = Original Price × (1 - decrease%)
New Price after increase = Original Price × (1 + increase%)
Percentage Change = $$\frac{(Final\ Price - Original \ Price) }{(Original \ Price)} × 100$$​​

Solution:

Let the original price be 100 units.
After 1st month decrease of 40%:
Price = 100 × (1 - 0.40) = 60 units
After 2nd month decrease of 50%:
Price = 60 × (1 - 0.50) = 30 units
After 3rd month decrease of 15%:
Price = 30 × (1 - 0.15) = 25.5 units
After 4th month increase of 40%:
Price = 25.5 × (1 + 0.40) = 35.7 units
Percentage change = $$(\frac{(35.7 - 100) }{ 100})$$​ × 100 = -64.3%

Therefore, the price decreased by 64.3% compared to the original price.