Myths
The Weight of the Statue
Story Summary
This is a riddle: “A statue weighs one ton plus half its weight. How much does the statue weigh?”
About the Story
At first glance, this riddle looks simple—but it tricks our intuitive reasoning. The answer that immediately comes to mind (1.5 tons) is incorrect.
It illustrates the value of making mistakes in mathematics and encourages students to learn through successive trials.
👉 Explore the story
Maths
An Unknown in the Equation… et a Tricky Statue
👦🏻 Target Age : 9–12 years (Grades 4-5)
⏰ Estimated Duration : 30 minutes
📎 Materials Needed : none
🎯 Learning Objectives
Develop the following math skills :
- Investigating
- Modeling
- Calculating
Develop the following life skills :
- Self-confidence
- Perseverance (trying again)
🔢 Mathematical concepts
- Understanding unknowns and equations
- Questioning intuitive answers
- Solving by trial and error
- Using models
🟢 Activité 1. Trial and Error
Assumed weight | Half the weight | 1t +half the weight | Result |
1,5t | 0,75t | 1,75t | Too light |
1,6t | 0,8t | 1,8t | Too light |
1,7t | 0,85t | 1,85t | Too light |
1,8t | 0,9t | 1,9t | Too light |
1,9t | 0,95t | 1,95t | Too light |
2t | 1t | 2t | Correct |
🟢 Activité 2. First Modeling
The image shows the equality: a statue weighs one ton + half its weight.
If we remove half a statue from each side, we see:
Half a statue weighs one ton.
Therefore, the whole statue weighs 2 tons.
🟢 Activité 3. Going Further: Solving with an Equation
$x = 1 + \frac{1}{2} \times x$
$x - \frac{1}{2} \times x = 1$
$\frac{1}{2} \times x = 1$
$x = 2$
The statue weighs two tons.