Free Practice Question
PS · Problem Solving
705-805
Divisibility/Multiples/Factors
The number of water lilies on a certain lake doubles every two days. If there is exactly one water lily on the lake, it takes 60 days for the lake to be fully covered with water lilies. In how many days will the lake be fully covered with lilies, if initially there were two water lilies on it?
Answer Choices
Correct answer marked belowA
15
B
28
C
30
58
Correct
E
59
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Explanation
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Official Explanation
Official
The number of water lilies doubles every two days.
Starting from 1 water lily, it takes 60 days to fully cover the lake.
If we start with 2 water lilies instead of 1, that is equivalent to having already completed one doubling period (2 days) from the single lily scenario.…
Starting from 1 water lily, it takes 60 days to fully cover the lake.
If we start with 2 water lilies instead of 1, that is equivalent to having already completed one doubling period (2 days) from the single lily scenario.…
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What it tests
Your understanding of divisibility rules, least common multiples, and greatest common factors.
Common trap
Forgetting that 1 is not prime and that every integer divides 0.
Details
Difficulty
705-805
Type
PS
Category