GCSE Maths Ratio and Proportion

Units of Measurement

Converting Units of Time

Converting Units of Time

Here we will learn about converting units of time, including converting between seconds, minutes and hours.

There are also worksheets based on Edexcel, AQA and OCR exam questions, along with further guidance on where to go next if you’re still stuck.

What is converting units of time?

Converting units of time is converting between seconds, minutes and hours.

To do this we need to know how different units of time are related to each other:

1 day = 24 hours

1 hour = 60 minutes

1 minute = 60 seconds

E.g

Convert 4 hours to minutes.

4 \times 60=240

4 hours = 240 minutes

How to convert units of time

In order to convert units of time:

1. Check the units involved.
2. Multiply or divide by the conversion factor.
3. Write the answer.

Converting units of time examples

Example 1: days to hours

How many hours are there in 1.5 days?

1. Check the units involved.

1 day = 24 hours

So the conversion factor is 24.

2Multiply or divide by the conversion factor.

We need to multiply by 24.

1.5 \times 24=36

1.5 days is 36 hours

Example 2: hours to minutes

How many minutes are there in 2.3 hours?

1 hour = 60 minutes.

So the conversion factor is 60.

We need to multiply by 60.

2.3 \times 60=138

2.3 hours is 138 minutes

Example 3: hours >>> hours and minutes

Convert 1.4 hours to hours and minutes.

1 hour = 60 minutes.

So the conversion factor is 60.

We need to concentrate on the decimal part of the original number, 0.4.

We multiply by 60 to convert to minutes

0.4 \times 60= 24

1.4 hours is 1 hour 24 minutes

Example 4: minutes to hours

Convert 324 minutes to hours.

1 hour = 60 minutes.

So the conversion factor is 60.

We need to divide by 60.

324 \div 60=5.4

324 minutes is 5.4 hours

Example 5: minutes >>> hours and minutes

Convert 520 minutes to hours and minutes

1 minute = 60 seconds

So the conversion factor is 60.

We need to divide by 60.

520 \div 60= 8.66666..... = 8\frac{2}{3}

There are 8 full hours and \frac{2}{3} of an hour.

Let’s convert  \frac{2}{3} of an hour to minutes by multiplying by 60.

0.66666… \times 60 =\frac{2}{3}\times 60 = 40

520 minutes is 8 hours and 40 minutes

Example 6: hours and minutes  >>> hours

Convert 2 hours and 45 minutes to hours.

1 hour = 60 minutes.

The conversion factor is 60.

We need to concentrate on the minutes part and convert it to hours by dividing by 60.

45\div 60=\frac{45}{60}=0.75

2 hours and 45 minutes is 2.75 hours

Common misconceptions

• Base \bf{10} and base \bf{60}

A common misconception is to confuse the units used in the metric system with the units used for time.

The metric system uses base 10 .

Each successive unit is 10 times larger than the previous one.

E.g.

Time uses base 60.

E.g.

Practice converting units of time questions

1. How many hours are there in 2\frac{1}{2} days?

60 hours

48 hours

72 hours

63 hours

2\frac{1}{2}\times 24=60

2. How many minutes are there in 3.1 hours?

31 minutes

190 minutes

186 minutes

310 minutes

3.1\times 60=186

3. Convert 4.35 hours to hours and minutes?

4 hours and 35 minutes

4 hours and 25 minutes

4 hours and 21 minutes

4 hours and 28 minutes

Concentrate on the decimal fraction part

0.35\times 60=21

So, 4.35 hours is 4 hours and 21 minutes.

4. Convert 75 minutes to hours?

0.75 hours

1.5 hours minutes

7.5 hours

1.25 hours

75\div 60=1.25

5. Convert 135 minutes to hours and minutes?

13 hours and 5 minutes

1 hours and 35 minutes

2 hours and 25 minutes

2 hours and 15 minutes

135\div 60=2.25

So there are 2 hours.

0.25\times 60=15

And there are 15 minutes

6. Convert 4 hours and 18 minutes to hours?

4.3 hours

4.18 hours

4.2 hours

4.81 hours

First look at the minutes

18 \div 60=0.3

So the minutes are 0.3 hours.

Altogether there are 4.3 hours.

Converting units of time GCSE questions

1. How many days are 120 hours?

A             B            C           D

Circle the correct answer.

(1 mark)

120\div 24=5

C – 5 hours

(1)

2. (a) Write 102 minutes as hours

(b) Write 2 hours and 48 minutes as hours.

(4 marks)

(a)

102\div 60

(1)

1.7 hours

(1)

(b)

48\div 60=0.8

(1)

2.8 hours

(1)

3. Work out how many seconds there are in 3 hours.

(2 marks)

3\times 60 \times 60

(1)

10 \ 800 seconds

(1)

Learning checklist

You have now learned how to:

• Change between standard units of time

Still stuck?

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FREE GCSE Maths Practice Papers - 2022 Topics

Practice paper packs based on the advanced information for the Summer 2022 exam series from Edexcel, AQA and OCR.

Designed to help your GCSE students revise some of the topics that will come up in the Summer exams.