Nutty mixture
Use the ratio of cashew nuts to peanuts to find out how many
peanuts Rachel has. What would the ratio be if Rachel and Marianne
mixed their bags?
Age
7 to 11
Challenge level
Problem
Image
Rachel has a bag of nuts.
For every cashew nut in the bag, there are two peanuts.
There are 8 cashews in Rachel's bag. How may peanuts are there?
Marianne also has a bag of nuts.
In Marianne's bag, for every two cashew nuts, there are three peanuts.
Marianne's bag contains 12 peanuts in total. How many cashews are in her bag?
In Marianne's bag, for every two cashew nuts, there are three peanuts.
Marianne's bag contains 12 peanuts in total. How many cashews are in her bag?
Rachel and Marianne decide to mix their bags of nuts together.
What is the ratio of cashew nuts to peanuts in the mix?
Getting Started
Might it help if you group the nuts?
Have you tried using counters or cubes to stand for nuts? Or perhaps you could draw a picture?
Have you tried using counters or cubes to stand for nuts? Or perhaps you could draw a picture?
Student Solutions
A lot of you had a really good attempt at this question. In addition to Ruth, Tom and Ollie (whose solutions are given below), well done to those of you who got the answer correct:
Talia and Maelona from Jebel Ali school, Dubai; Tom from C.P.S.; Katie, Oliver and Daniella from Portsmouth Grammar School; Amy from Stoke by Nayland Middle School; Daniel from Camberwell South Primary School, Melbourne, Australia; Zak from Clavering Primary School; Andrew Mott from Aldermaston C.E. primary school; Alice and Miriam from Aldermaston Primary; Alara from IK Primary School; Jason (school unknown) and Ben from Short Wood Primary School.Ruth from Oxford High sent in this clearly explained solution:
In the first problem Rachel has double the number of peanuts to cashew nuts. She has 8 cashew nuts in her bag so you double the number of cashew nuts and you get 16 peanuts.In the second problem Marianne also has a bag of nuts but this time she has 3 peanuts for every 2 cashew nuts. Marianne has 12 peanuts which is 4 times bigger than 3. So she will have 8 cashew nuts because this is 4 times bigger than 2.
When you add the two bags together they make the following:
| Bag Owner | Cashews | Peanuts |
| Rachel | 8 | 16 |
| Marianne | 8 | 12 |
| Total | 16 | 28 |
16 : 28 = 4 : 7
Because both 16 and 28 can be divided by 4, the ratio in its simplest form is 4 : 7
Tom and Ollie of Ardingly College had a slightly different way of explaining it:
Q1: Rachel's bag of nuts should contain 8 cashews and 16 peanuts. We found this out by doubling the cashews and converting them to peanuts.
Q2: Marianne's bag of nuts should contain 12 peanuts and 8 cashews we found out how many cashews there were by working through the amounts in stages. These are our workings out:
2-3
4-6
6-9
8-12
Q3: Rachel and Marianne's bag of mixed nuts should contain a cancelled down ratio of 4:7 (left = cashews right = peanuts). We worked this out by adding the different nuts up in groups; the uncancelled ratio was 16:28. We cancelled the ratio down twice.
How to do the last section:
To do this last part you must know all the amounts of peanuts and cashew nuts in both girls' bags. The nuts from Rachel's bag were 8 cashew nuts and 16 peanuts and from Marianne's bag were 8 cashew nuts and 12 peanuts. Next you must add the amount of peanuts together which makes 28 peanuts and the amount of cashew nuts which gives the answer of 16 peanuts. This should be written as 28:16 or
16:28 which can be reduced by the number which goes into them both by dividing them. You will know your answer when no number goes into both of them.
Teachers' Resources
Nutty Mixture
Image
Rachel has a bag of nuts.
For every cashew nut in the bag, there are two peanuts.
There are 8 cashews in Rachel's bag. How may peanuts are there?
Marianne also has a bag of nuts.
In Marianne's bag, for every two cashew nuts, there are three peanuts.
Marianne's bag contains 12 peanuts in total. How many cashews are in her bag?
In Marianne's bag, for every two cashew nuts, there are three peanuts.
Marianne's bag contains 12 peanuts in total. How many cashews are in her bag?
Rachel and Marianne decide to mix their bags of nuts together.
What is the ratio of cashew nuts to peanuts in the mix?