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Ratio of 2 hours to 40 minutes

Step by step, with the reason for every step · Ratios with units · Foundations

Step by step

The question

Question: write the ratio of 2 hours to 40 minutes in its simplest form.

2 hours : 40 minutes

Careful!

The units are not the same: hours and minutes.

2 to 40 would compare different things.

Careful: not 2 : 40 ✗

1 Same units

A ratio only compares amounts in the same unit.

We change to the smaller unit, minutes, so there are no fractions.

1 hour is 60 minutes.

1 hour = 60 minutes

So 2 hours is 2 times 60: 120 minutes.

= 2 hours = 2 × 60 minutes = 120 minutes

2 Drop the units

Now the ratio is 120 minutes to 40 minutes.

= 120 minutes : 40 minutes

Both are in minutes.

The same units cancel, so we cross them out.

That leaves 120 to 40.

= 120 : 40

3 Simplify

120 and 40 can both be divided by 40.

We divide both parts by 40.

The ratio stays the same.

= 120 ÷ 40 : 40 ÷ 40

120 divided by 40 is 3.

40 divided by 40 is 1.

So the ratio is 3 to 1.

= 3 : 1

4 Check

Let's check: times each part by 40.

We get 120 minutes and 40 minutes again.

3 × 40 = 120 minutes, 1 × 40 = 40 minutes

And 120 minutes divided by 60 is 2 hours, as in the question.

So the answer is right!

120 minutes = 120 ÷ 60 = 2 hours

Let's look back.

First: same units.

Then: drop the units.

Then: simplify.

Last: check.

Answer
= 3 : 1

Your turn

Try this one yourself, then check:

3 hours : 40 minutes
Show the answer
9 : 2

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