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Numerical Ability
Permutation and Combination
In a staircase, there are 10 steos. A child is attempting to climb the staircase. Each time she can either make 1 step or 2 steps. In how many different ways can she climb the staircase?
Option
a) 10
b) 21
c) 36
d) None of these
Read Solution (Total 6)
-
- Use Fibonacci series because the child make 1 step or 2step.
1,2,3,5,8,13,21,34,55,89.
The number of ways she can climb the staircase is 89.
so the answer is d)None of these - 10 years agoHelpfull: Yes(16) No(13)
- 1 1 1 1 1 1 1 1 1 1(just one way)
1 1 1 1 1 1 1 1 2(9C1=9 way)
1 1 1 1 1 1 2 2(8C2=28 way)
1 1 1 1 2 2 2 (7C3=35 way)
1 1 2 2 2 2(6C4=15 way)
2 2 2 2 2(1 way)
so total way(1+9+28+35+15+1)=89 way - 10 years agoHelpfull: Yes(14) No(1)
- 89 is correct
- 10 years agoHelpfull: Yes(4) No(3)
- ans d;
only 6 ways r possible.
1.taking only single steps 1*10 so 1 way
2.taking only 2 steps at a time i.e;2*5=10 steps,so 1 way
3.taking both 1&2 steps combntn i.e, 2*1+4*2=10, 4*1+3*2=10, 6*1+2*2=10, 8*1+1*2=10 SO ,4 ways. hence total 6 ways r possible
2. - 10 years agoHelpfull: Yes(1) No(1)
- 10 steps
one step/ two steps
9 8
/ /
8 7 7 6
if we do in this way we will get the answer as 89 - 10 years agoHelpfull: Yes(0) No(0)
- she can either make 1 step or two step=n(aub)=n(a)+n(b)_n(a)*n(b)=10+10/2-10/2=10 so a is the ans
- 10 years agoHelpfull: Yes(0) No(3)
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