Education
Age Range: 14-16
Duration: 0-29 mins
• Mathematics

# Is it worth converting to LPG?

## Use mathematical calculations to decide whether it is worth switching to an alternative fuel

Can you use data to determine whether it is worth converting to LPG?

Download our free fuel consumption worksheet below to take part in this engaging activity. This is a great way for GCSE students to learn about fuel efficiency and develop their problem-solving skills.

## Activity: Is it worth converting to LPG?

Download the presentation below and allow the students to read the problem on the first slide. Let them think about what criteria they can use to decide whether it’s worth converting to LPG. They should take into account the annual mileage, price of petrol or LPG at the local station and size of the car in question.

They should consider the amount of money saved by converting vs the cost of the conversion. Some students may want to examine the time it would take to recover the cost of converting the car. They also need to be aware that “a car uses 10% more LPG than petrol when driving the same distance.”

This activity will encourage students to use their problem-solving skills. Understanding what information is needed and how to use the information is a key part of problem solving.

### Discussion points

Encourage discussion about which type of car saves most and get them to think about why this is. Remember they all do the same annual mileage! If students don’t consider recovering the cost of conversion, then prompt them at some point.

### Extending the problem

It is possible to use the spreadsheet to produce a graph showing how the savings vary with annual mileage. Students could investigate the fluctuations in LPG and petrol prices over time to see if this would influence their decision.

## Potential GCSE content covered

In this activity learners will use and apply calculations, use compound measures, calculate the percentage of an amount and consider the application of algebra to spreadsheets.

### What is LPG?

LPG is a by-product of crude oil extraction and the refining process. Many people who consider LPG as an alternative to petrol do so because they believe that the combustion of propane results in lower carbon dioxide emissions. In terms of fuel costs, LPG costs a little more than half the price of petrol or diesel, but fuel economy is about 20-25% lower. Therefore, the overall running costs of an LPG car is approximately a third less than a petrol only car – but only once you’ve recovered the cost of the conversion.