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4.10 B) Unit Conversion – Part 2

4.10 B) Unit Conversion – Part 2

We are going to be looking at some examples in this section whereby we are given the unit conversion in the question. We are usually given conversions in the form of 1 = n. An example would be:

Here are the calculations for the two different conversions:

There is more information about these types of conversions in the previous section. Click here if you would like to be taken through to the previous section.

- If we are converting from miles to km (converting the unit that is 1 into the n unit), we multiply by 1.6.
- If we are converting from km to miles (converting the n unit into the unit that is 1), we divide by 1.6.

There is more information about these types of conversions in the previous section. Click here if you would like to be taken through to the previous section.

**Example 1**

I am 12.8 stone. What is my weight in kilograms? Use the conversion that 1 stone is equal to 6.35 kilograms.

We are told in the question that 1 stone is equal to 6.35 kilograms, and this gives us the following conversion:

We are asked in the question to convert stone to kilograms (to convert the unit that is 1 to the n unit), and we are able to do this by multiplying by 6.35. The working is shown below:

12.8 stone in kilograms is 81.28 kilograms.

**Example 2**

I lift a 30-pound weight. What is this weight in pounds? Use the conversion that 1 pound is equal to 0.454 kg and give your answer to 1 decimal place.

We are told in the question that 1 pound is equal to 0.454 kg and this gives us the following conversion:

We want to convert kilogram into pounds (we want to convert the n unit to the unit that is 1), which we are able to do by dividing by 0.453. The working is shown below:

We are asked to give the answer to 1 decimal place.

Therefore, 30 kilograms in pounds is 66.1 pounds.

**Example 3**

I go for a 9.3 mile run on Tuesday and a 15 km run on Friday. On which day did I run the furthest? Use the conversion that 1 mile is 1.6 km.

The best way to establish which day I ran the furthest is to have both of these distance in the same unit and then compare the two values. It does not matter if we get both of the runs in terms of miles or both of the runs in terms of kilometres; I will do both so that you can see that it does not matter which unit we get the distances in.

**Into Miles**

The run on Monday is already in miles, which means that we do not need to do anything.

The run on Tuesday is 15 kilometres and we want to convert it from kilometres into miles. We are told in the question that we are to use the conversion 1 mile is 1.6 km, and this gives us the following unit conversion:

We want to convert kilometres into miles (we are converting the n unit to the unit that is 1) and this means that we divide by 1.6. The working is shown below:

Therefore, on Friday I ran 9.375 miles. This value is greater than the 9.3 miles that I ran on Tuesday, which means that I ran the furthest on Friday.

I am now going to get both of the runs into kilometres.

The run on Tuesday is 9.3 miles and we want to have the distance in kilometres. We are told in the question that 1 mile is 1.6 km, which gives us the following unit conversion:

**Into Kilometres**I am now going to get both of the runs into kilometres.

The run on Tuesday is 9.3 miles and we want to have the distance in kilometres. We are told in the question that 1 mile is 1.6 km, which gives us the following unit conversion:

We are converting miles into kilometres (we are converting the unit that is 1 to the n unit), which means that we multiply by 1.6. The working is shown below:

On Tuesday, I ran 14.88 km. This distance is less than the distance that I ran on Friday (15 km), which means that I ran a greater distance on Friday.

We obtained the same answer (that Friday was the longer run) whether we had both of the distances in miles or both of the distances in kilometres.

We obtained the same answer (that Friday was the longer run) whether we had both of the distances in miles or both of the distances in kilometres.

**End Note:**

In the previous section, we looked at some metric unit conversions that you need to remember. These unit conversions are:

- 1 cm = 10 mm
- 1 m = 100 cm
- 1 km = 1,000 m
- 1 litre = 1,000 ml
- 1 kg = 1,000 g

In addition to these, I think that it is also worth remember the following approximate conversions between metric and imperial units:

- 1 mile ≈ 1.6 km ≈1,600 m
- 1 inch ≈ 2.5 cm

*The symbol “≈” means approximately equal to*