### Become an OU student

Ratio, proportion and percentages

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

# 1.3 Using ratios

Time conversions are also ratios. The ratio of time measured in minutes to time measured in seconds is one to sixty (1:60), as there are sixty seconds in a minute.

## Example 2

Adam's grandfather ran a mile in minutes. Adam took 260 seconds. Which is greater, 260 seconds or minutes? Did Adam run faster than his grandfather?

minutes is equivalent to × 60 seconds.

is equivalent to . So this is × 60 = 270 seconds.

So minutes is just a bit longer than 260 seconds. Therefore Adam has run faster than his grandfather.

When shopping for a bargain, the ratio of price to quantity is often a useful way of comparing prices of different sized packets.

## Example 3

A local shop sells ready-made custard at £1.45 for a special offer pack of three 425 g tins. It also sells the same brand of custard in 1 kg cartons costing £1.29 each. Which is the better bargain?