Weighing Fruit
Can you use this information to estimate how much the different fruit selections weigh in kilos and pounds?
Problem
There are some open markets in England that would like to sell fruit by their weight in lbs (pounds), but we often buy them in kilos.
0.45 kilo = 1 lb
2.20 lb = 1 kilo
You get about 4 apples or 4 bananas in one pound (1 lb).
So, roughly, what would 6 bananas and 4 apples together weigh in kilos?
You get about 6 mangoes in a kilo.
So, roughly, what would 30 mangoes weigh in pounds (lbs)?
You get about 6 oranges in one pound (1 lb).
So, roughly, what would 20 oranges weigh in kilos?
Getting Started
Is a kilo bigger, the same, or smaller than a pound? How do you know?
How much would 4 apples weigh in kilos?
So, how can we find the answer to the first question?
How much do 6 oranges weigh in pounds? So, how can we find the answer to the second question?
What would you like to do?
Student Solutions
We had 17 replies to this problem, but most were not quite right and had some "slip ups" in them. Some answers did not get to the required units of measure. Others multiplied numbers together that shouldn't have been multiplied. However thank you for all the contributions. We can always learn from our mistakes.
Two of the five correct answers are shown below.
Michael
These are the basic calculations and answers
1. 6s+4s=10/4=2.5 =2.5lb = 2.5*0.45 = 1.125kg =10s
2 6m =1kg 30m=5kg 5*2.20= 11lb= 30m
3.6o= 1lb 20o in kg 3.3*6=20 3.3lb=1.5 kg
Claudia
1lb for 4 apples
1lb for 4 bananas
1 and a 1/2 lb for 6 bananas
4 apples and 6 bananas would weigh 2 ½ lb altogether
You get about 6 mangos in a kilo.
So, roughly, what would 30 mangos weigh in pounds (lbs)?
2.20 lb= 1 kilo
1 kilo=6 mangos
6 mangos= 2.20lb
5x6=30
5x 2.20
5x2= 10
5x 0.20= 1
30 mangos would weigh 11lbs
You get about 6 oranges in one pound (1 lb).
So, roughly, what would 20 oranges weigh in kilos?
1lb for 6
0.45 kilos for 6
0.45 x 3.2=1.44
20 oranges weigh 1.44 kilos
Teachers' Resources
Using NRICH Tasks Richly describes ways in which teachers and learners can work with NRICH tasks in the classroom.
Why do this problem?
Possible approach
Key questions
Possible extension
Possible support
Having balances and scales available for pupils to get a sense of the conversions would be helpful, and this might allow them to check that their answers seem reasonable too.