Question

Q.14)
Vishwa is walking up a stair that has 10 steps and with each stride he goes up either one step or two steps. The number of different ways Vishwa can go up the
stars is​

Answer 1

Given:

Steps in the stairs = 10

To Find:

Different ways Vishwa can climb the stairs

Solution:

Vishwa goes one or two steps up, thus -

Number of way to climb by only one step = 1

Number  of ways  to select two step in nine moves

= 9C1

= 9

Number  of ways to select   two 'two steps in eight moves

= 8C2

= 28

Number  of ways  to select three 'two steps' in seven moves

= 7C3

= 35

Number  of ways  to select four 'two steps' in six moves

=  6C4

= 15

Number  of ways  to select five  'two steps' in five moves

= 5C5

= 1

Therefore,

Total number of  ways = 1 + 9 + 28 + 35 + 15 + 1

= 89

Answer: Vishwa can go up the stairs in 89 ways.