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shalini goyal Grade: 12

a flight of stairs has 10 steps.a person can go up the steps one at a time ,two at a time,or any combination of 2's and 2's.find d total number f wayz in which d person can go up d stairs??? plz give me complete soln for dis....cuz i got d ans bt prob z m nt sure about the way i solved it!! ans is:89
do reply....plzz!!

7 years ago

Answers : (1)

AskiitiansExpert Mohit-IITD
21 Points

Dear Shalini,

There are 10 steps, so following cases are possible:

10 single steps =1

1 double steps, 8 single steps = 9!/8! =9

2 double steps, 6 single steps = 8!/6!2!=28

3 double steps, 4 single steps = 7!/4!3!=35

4 double steps, 2 single steps = 6!/4!2!=15

5 double steps = 1


Hope this helps.

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7 years ago
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