Depth · one concept from first principles · step 2 of 4
A container holding of milk weighs . After of milk is poured out, it weighs . How many kilograms does the empty container weigh?
The difference between the two weighings is only the milk that was poured out, because the container is in both.
2.4 L of milk weighs 2.52 kg.
6.NS.B.3Identify SubproblemsThe difference between the two weighings is only the milk poured out.
Each weighing is the container plus the milk in it at that moment, and the container itself never changes.
Taking the second from the first therefore removes the container from both sides at once and leaves the milk that went.
Divide that weight by the number of liters poured out.
One liter of milk weighs 1.05 kg.
6.RP.A.2Analyze The UnitsSix liters at that weight each.
The milk alone was 6.3 kg.
6.RP.A.2Work BackwardsWhat is left of the first weighing is the container.
The empty container weighs 0.57 kg.
6.NS.B.3Identify SubproblemsSubtracting two measurements that share the same hidden weight makes that weight disappear.
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