Mammoth Memory

3 part ratio and dividing up amounts

Ratios are used to divide a large amount up. The best way to tackle these are

 Work out 1 part
by adding all the ratios

Example 1

If `$6.00` is divided between three people in the ratio Karen 4: Alice 5: Brenda 6 what do they each get?

So the ratio is `4:5:6`

Add the ratio `=4+5+6=15` parts in all

Now work out `1` part

(see our section on percentages for full explanation)

`15` parts `=$6.00`

    `1` part `=x`

Now put the divide sign in

`15/1=($6.00)/x`

Rearrange

`x=($6.00times1)/15`

`x=$0.40`

Therefore

Karen 4 `=4times$0.40=` `$1.60`
Alice 5 `=5times$0.40=` `$2.00`
Brenda 6 `=6times$0.40=` `$2.40`
   
  Total    `$6.00`

 

Example 2

The ratio of adults to children in a school bingo is 4 to 1. The ratio of adults to pensioners is 4 to 3. If there are 96 people in total how many people are there of each group?

So the ratio is `=4` Adults to every `1` child to every `3` pensioners

`4:1:3`

Add the ratio `=4+1+3=8` parts

Now work out `1` part

(see our section on percentages for full explanation)

`8` parts `=96` people

  `1` part `=x`

Now put the divide sign in

`8/1=96/x`

Rearrange

`x=(96times1)/8`

`x=12`

Therefore

Adults 4 `=12times4=` `48`
Children 1 `=12times1=` `12`
Pensioners 3 `=12times3=` `36`
   
  Total    `96`

 

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