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Example Video Questions Lesson Share to Google Classroom Example Video Questions Lesson Share to Google Classroom
To calculate the ratio of an amount we divide the amount by the total number of parts in the ratio and then multiply this answer by the original ratio.
Supporting Lessons
Ratios describe how to share out a given amount and are written with numbers separated by colons. The amount of numbers in the ratio tells us how many groups the quantity is being shared between. The size of each number tells us the proportion of the total amount each group gets. For example, in the ratio 1:3 there are two different numbers: ‘1’ and ‘3’. Because there are two numbers, we are sharing an amount between two people. This ratio means that for every 1 part that the person on the left gets, the person on the right gets 3. The person on the right will have three times as much as the person on the left.
The person on the left will get $5 and the person on the right will get $15. Both numbers add to make the total of $20 but $15 is three times larger than $5. This is why the ratio is 1 to 3. How to Calculate a Ratio of a Number in StepsTo calculate a ratio of a number, follow these 3 steps:
For example, share $20 in the ratio 1:3.
This means that in this ratio problem, we will be sharing $20 between two people with one person getting three times as much as the other. We follow the 3 steps above to work out the ratio.
Looking at the ratio 1:3, we have: 1 + 3 = 4 So, we have four parts in total in our ratio.
The amount is $20 and the total number of parts is 4. 20 ÷ 4 = 5 Each of the four parts is worth $5.
We have four parts in total and each of these parts are worth $5. We will multiply both numbers in the ratio 1:3 by $5. 1 x $5 = $5 3 x $5 = $15 The money is shared in the ratio $5:$15. We have solved our ratio problem to find that one person gets $5 and the other person gets $15. To check a ratio calculation, add the final values to see if the total is equal to the original amount. If the amounts shared can also be simplified to make the ratio given, the calculation is correct. $5 + $15 = $20, which is the amount that we started with, so we can be confident that our calculation is correct. To confirm our ratio calculation, we check that $5:$15 simplifies to give us our original ratio. Dividing both $5 and $15 by 5, gives us 1:3, which is our original ratio and $15 is indeed three times as much as $5.
Now try our lesson on Sharing in a Ratio Between 3 People where we learn how to extend our steps for calculating ratio to examples where we share an amount between 3 people.
Sharing in a Ratio Between 3 People
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