Sharing an Amount in a Ratio

0:00How do you share 60 dollars in the ratio 2 to 3?

0:05A ratio compares amounts. 2 to 3 means Ava gets 2 parts for every 3 parts Ben gets, and every part is the same size.

0:15First, add the parts of the ratio. 2 plus 3 makes 5 parts in total.

0:21Next, find one part. Divide the amount by the total number of parts: 60 dollars divided by 5 is 12 dollars.

0:31Then multiply. Ava gets 2 times 12, which is 24 dollars. Ben gets 3 times 12, which is 36 dollars.

0:41Check: 24 dollars plus 36 dollars is 60 dollars, the whole amount.

0:50A ratio can compare three amounts too. Cut a 105 centimetre string in the ratio 3 to 5 to 7.

0:59The first piece gets 3 parts, the second gets 5 parts and the third gets 7 parts.

1:06Add the parts: 3 plus 5 plus 7 is 15 parts.

1:12Find one part: 105 divided by 15 is 7, so each part is 7 centimetres.

1:20Then multiply each number in the ratio by 7. 3 times 7 is 21, 5 times 7 is 35, and 7 times 7 is 49 centimetres.

1:33Check: 21 plus 35 plus 49 is 105 centimetres, the whole string.

1:40A common mistake is to divide by the number of pieces instead of the number of parts.

1:48105 divided by 3 is 35, which makes three equal pieces. That is not the ratio 3 to 5 to 7.

1:58To find one part, divide by the total number of parts. Here that is 15, not 3.

2:07To share in a ratio, add the parts, find one part, then multiply.