Video: Comparing the Masses of Two Objects in Kilograms

Fill in the blank: The mass of the box of books is _ kg heavier than the mass of the box of toys. The mass of the box of books is 31 kg. The mass of the box of toys is 25 kg.

02:06

Video Transcript

Fill in the blank: The mass of the box of books is what kilograms heavier than the mass of the box of toys. And then we’re given two sentences to help us. The mass of the box of books is 31 kilograms. The mass of the box of toys is 25 kilograms.

In this question, we’re shown two boxes. And we don’t need to weigh them to find out how heavy they are because we’re told that the mass of the box of books is 31 kilograms and the mass of the box of toys is 25 kilograms. Now, we know that the number 31 is a larger number than 25. And because both masses are measured in kilograms, all we have to do to compare them is to just look at these numbers. We know that the mass of the box of books then is heavier than the mass of the box of toys. It weighs more. 31 kilograms is heavier than 25 kilograms.

Now, we’re given a sentence that we need to complete. The mass of the box of books is what kilograms heavier than the mass of the box of toys. In other words, we know that the books weigh more. But how much more? Let’s count backwards from 31 kilograms to 25 kilograms to see. We could make a jump of one to go from 31 back to 30. And then we know to go from 30 to 25 is a jump of five. So we’ve made a jump of one and then a jump of five. How many kilograms is that? It’s six, isn’t it? The difference between 25 kilograms and 31 kilograms is six kilograms. And so we can say the mass of the box of books is six kilograms heavier than the mass of the box of toys. The missing number is six.

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