Weight calculation

Weight calculation

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This task is about using algebra to solve maths problems.
 
illustration: Three dogs: Kuri, Max and Poppy
Kuri got on some scales with Poppy, and together they weighed 100 kg. Poppy weighed 3 times as much as Kuri.
Here is a statement in algebra describing what happened:
3y + y = 100

Question 2Change answer

a)  How heavy was Poppy?   kg
b)  How heavy was Kuri?  kg
c)  What does the 3y stand for?  

Question 2Change answer

Poppy, Max and Kuri all got on the scales.
d)  Max was half the weight of Kuri. What did Max weigh?   kg
e)  How much would all three dogs weigh together?    kg
Task administration: 
This task is completed with pencil and paper or online with lots of auto-marking.
Copyright: 
Image: iStock
Level:
4
Curriculum info: 
Maths, Number and Algebra, Equations and expressions
Keywords: 
linear equations, algebraic expressions, pronumerals, dogs
Description of task: 
Students identify parts of an algebraic equation and use the equation to calculate dog's weights for a given total.
Answers/responses: 
 

Y8 (06/1996)

Y9 (06/1996)
a) 75 difficult difficult
b) 25 moderate moderate
c) The weight of Gail's father [in kg]
or 3 times Gail's weight.		 moderate difficult
d) 12.5 
or 12 1⁄2 kg; 12 500 g; 12 kg and 500 g.
[Accept half of the answer to b).]		 moderate moderate
e) 112.5
or 112 1⁄2 kg; 112 kg and 500 g.
[Accept 100 kg plus the answer to d).]		 moderate moderate