rohit8865 wrote:

Bunuel wrote:

If the price of gasoline increases by 25% and Ron intends to spend only 15% more on gasoline, by how much percent should he reduce the quantity of gasoline that he buys?

A. 6.66%

B. 8%

C. 10%

D. 12%

E. 12.5%

Let he consumes 10 ltr

RS 10 so he spends Rs 100

As er question he intends to spend 15% more (of 100 in our case)=Rs 115

and price increased by 25% =Rs. 12.5 (10+25% of 10)

let he reduces quantity by X lts. then consumed(new reduced) quantity= 10(1-X/100)

Spending amount=Price of gasoline*Quantity

115=12.5*10(1-X/100)

X=8%

Ans B

For wondering minds, "Rs" in the solution above is short for "Rupee" - a monetary unit in India.

This is how I solved...

Let the initial cost of gas before the hike be $100/gal

Price hike given = 25%

=> New gas price per gallon is $125

Also given, Ron can only spend 15% more of what he used to afford. It is to be understood from the prompt that he was able to afford a full gallon (which means he used to get 1 gal of gas) before the hike. So, he was able to afford $100 before the hike but now he can only afford 15% more of $100. Therefore, he could only pay $115.

You get what you pay, so instead of getting a full gallon of gas, he will now only get 0.92 gal [For $125 you get 1 gal, for $115 - how many? => \(\frac{1}{125}\)*115].

Finally, find the percentage decrease in the amount of gas from before and now.

Percentage Decrease =\(\frac{0.92 - 1}{1}\)*100