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Chapter 9 · Questions · page 53 of 68

How do you split a number in a given ratio?

Short answerAdd the parts of the ratio, divide the total by that sum to get one part, then multiply. $40 in the ratio 2 : 3 is $16 and $24.

levelPre-algebra
standard6.RP.A.3
practiceRatios and rates

A ratio of 2 : 3 means the total is cut into 5 equal parts, with 2 going one way and 3 the other. Find the size of one part and the rest is multiplication.

How to use it

  1. Add the numbers in the ratio to get the number of parts.
  2. Divide the total by the number of parts.
  3. Multiply one part by each number in the ratio.
  4. Check the shares add back to the total.

Example

2+3=52 + 3 = 5
405=8\frac{40}{5} = 8
2×8=162 \times 8 = 16
3×8=243 \times 8 = 24
16+24=4016 + 24 = 40

Where it goes wrong

  • Dividing the total by 2 or by 3 instead of by 5.
  • Giving the size of one part as the answer.

Related

Unit ratesRatios and simplest form
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