Problem 15 · 2019 Math Kangaroo
Medium
Algebra & Patterns
substitution
A full glass of water weighs 400 grams. An empty glass weighs 100 grams. How much does a half-full glass of water weigh?
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Answer: D — 250 g
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Hint 1 of 2
The full glass weighs glass plus all the water; subtract the empty glass to get the water's weight.
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Hint 2 of 2
A half-full glass is the empty glass plus half the water.
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Approach: separate glass and water weights
- Water alone weighs 400 − 100 = 300 g.
- Half the water weighs 150 g.
- A half-full glass weighs 100 + 150 = 250 g (D).
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