1. What are Age Problems?
Recipe problems are simple direct proportion problems, where you are given the amount of various ingredients needed to make some food items. You need to figure out the amount of ingredients needed to make a different amount of the same food item. The trick is the ratio of amount of ingredients and amount of food always remains the same, so you just need to do simple multiplication and division to get the answers.
Example:
Here is a recipe to make 10 cookies
Work out how much of each ingredient is needed to make 100 cookies.
As you can see, if we multiply 10 cookies by 10 we will get 100 cookies, right? So here just multiply every ingredient by 10 and you will have your answer.
The recipe to make 100 cookies
The question was easy though, what if the question asked about the ingredients to make only 13 cookies? The best approach if the question is tough, get the amount needed to make only 1 food item (here a cookie). We can do that by dividing the amount of ingredients by the amount of food items and then multiplying by the number of food items being asked as shown below.
Calculating the recipe to make 1 cookie: -
As we got the ingredients of 1 cookie we can calculate the respective amounts for any number of cookies.
Now, the recipe to make 13 cookies will be: -
So basically there are only 2 steps involved in this method:-
Step 1: Divide every ingredient's amount by the amount of food items.
Step 2: Multiply by the amount of food items needed.
Solved Examples:
Example 1:
Jessica is making shortbread for 12 people.
She found the recipe on a website.
How much of each ingredient will she need for 12 people?
Solution:
As 12 ÷ 4 = 3, it's an easy question.
As the recipe for Shortbread is for 4 people, but we have 12 people to serve so we need more but how much?
12 ÷ 4 = 3, So we need 3 times the ingredients that have been given.
So she will need
Example 2:
James has a recipe for making Rice Krispie cakes.
The recipe uses 120g of chocolate and 80g of Rice Krispies to make 6 cakes.
How much chocolate should James use to make 17 cakes?
Solution:
As 17 is not divisible by 6, we will use the 2-step method here.
James needs 120g of chocolate to make 6 cakes so for 1 cake he will need
120g ÷ 6 = 20g
If for 1 cake he needs 20g then for 17 cakes he will need
20g × 17 = 340g of chocolate.
Now that you know all there is to know about Recipe Problems, apply the knowledge you gained and practice the past paper questions and quiz here.
