Problem 1 · 2015 Math Kangaroo
Easy
Logic & Word Problems
ages
Andrea was born sometime in the year 1997 and her sister Charlotte sometime in the year 2001. What is known for certain about the age difference of the two sisters? It is…
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Answer: E — not less than 3 years
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Hint 1 of 2
Push the two birth dates to their extremes to find the smallest and largest possible gap.
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Hint 2 of 2
Born in 1997 vs 2001 means the gap is bigger than 3 years but can fall short of 4.
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Approach: bound the age gap from both extremes
- The earliest Andrea could be born is start of 1997; the latest Charlotte is end of 2001, giving an age gap just under 5 years.
- The latest Andrea is end of 1997 and the earliest Charlotte is start of 2001, giving an age gap just over 3 years.
- So the gap is always more than 3 years; nothing stronger is guaranteed, so it is not less than 3 years (E).
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