Bucket of water

Lisa's bucket weighs 21 kg when full of water. After she pours out half the water it weighs 12 kg. What is the weight of the empty bucket?
Exploring and noticing Working systematically Conjecturing and generalising Visualising and representing Reasoning, convincing and proving
Being curious Being resourceful Being resilient Being collaborative

Problem



Lisa's bucket weighs 21 kg when full of water.

After she pours out half the water from the bucket it weighs 12 kg.

What is the weight of the empty bucket?

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.