Hi,

Can someone share a 2-3 set calculation for this problem? I am not sure about which number to divide and multiply 25 with. I often get confused with such problems.

Please share any tips.

Hi,

Can someone share a 2-3 set calculation for this problem? I am not sure about which number to divide and multiply 25 with. I often get confused with such problems.

Please share any tips.

Have you seen the solution to this problem?

Yes, there is no video solution but numerically it is (4.546/3.785)*25

Is there a problem with the text solution?

Also: for this one, think intuitively. Which would you be able to travel further: with a US gallon or a UK gallon?

Nope, one is always going to be greater than the other.

Hint: you know that the UK and US gallons can be represented in a unit we all know, the litre.

How I thought about it was by finding the total miles for US (25*3.785) and then dividing by the UK gallon units to find the miles per gallon in UK. However, I understand that in the solution the division and multiplication is opposite.

I wanted to understand how I can check my answer in problem where we make such mistakes and also how do I avoid this confusion all together?

You haven’t answered my previous question. Let’s put it this way: we know that

- 1 US gallon = 3.785 L
- 1 UK gallon = 4.546 L

You have a car with a fuel economy of (say) 8 km/L. How much can the car travel if you fill it with a US gallon, and a UK gallon, separately?

8 Km in 1 litre, therefore, 30.28 for US and 36.368 for UK.

Notice that you just found out that we can travel more with one UK gallon compared to one US gallon. Can you use that to derive a similar comparison between US mpg and UK mpg, as shown in the problem?

I really appreciate your patience but I am not so sure yet. I did get the first part though.

What did we find out from the first part? Given that a car has a fuel economy of 8 km/L, we can travel 30.28 km and 36.368 km on average when we fill the car with a US and a UK gallon of petrol respectively.

Notice that we’ve implied that we can travel further with a UK gallon compared to a US gallon. This makes sense, because a UK gallon has more petrol than a US gallon.

The question itself is similar. It says that the car can travel 25 miles with a US gallon. We know from the above discussion that a UK gallon contains more petrol than a US gallon. What do you think would happen to the mpg (miles per gallon) in the UK - would it be more or less?

Makes sense. It should be more.