Video: KS2-M17 • Paper 2 • Question 18

A cat sleeps for 12 hours each day. 50% of its life is spent asleep. Write the missing percentage. A koala sleeps for 18 hours each day. _% of its life is spent asleep.

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Video Transcript

A cat sleeps for 12 hours each day. 50 percent of its life is spent asleep. Write the missing percentage. A koala sleeps for 18 hours each day. What percent of its life is spent asleep?

We know that one day is equal to 24 hours. And the question tells us that a cat sleeps for 12 hours each day, or 12 out of 24 hours. 12 out of 24 is the same as saying half. And we know that a half is equal to 50 percent. Half a day is 50 percent of a day.

A koala sleeps for 18 hours each day. So we can write this as 18 over 24, or eighteen twenty-fourths. To help us calculate what percentage this is, first we need to simplify this fraction. We could divide the numerator and the denominator by two to give us nine twelfths. Then if we divide the numerator and the denominator by three, we can see the nine twelfths is equal to three-quarters.

If half is equal to 50 percent, we can use this to work out what a quarter is equal to, which is 25 percent. If one-quarter is 25 percent, we can multiply this by three to find three-quarters. 25 times three is 75. So a koala spends 75 percent of its life asleep.

To find the answer, first we’ve recognised that 12 out of 24 hours is half a day, which is the same as 50 percent. Using the information we were given, we worked out that a koala sleeps for 18 out of 24 hours, which is equal to nine twelfths, which is equal to three-quarters. We know that one-quarter is the same as 25 percent. So three-quarters is equal to 75 percent. A koala sleeps for 18 hours each day. 75 percent of its life is spent asleep.

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