Staircase climbs using jumps of two or more
Question
A rabbit stands at the bottom of a -step staircase. Every hop moves it up by at least steps (any number of steps that is or more). How many different sequences of hops take it exactly to the top of step ?
Short answer
. Count compositions of 10 into parts of size at least 2. If is the count for steps, removing the last stair from a final hop of size at least 3, or deleting a final hop of size exactly 2, gives with . That is a Fibonacci sequence and .
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Open the worked solutionLessons behind this question
- Counting and Combinatorics
- Sample Spaces, Events, and the Probability Axioms
- Conditional Probability, Total Probability, and Bayes' Rule
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