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Take into consideration a 12\times 13 grid with A as the starting point and B as the finishing point. Each step can either be an upward or a rightward movement. Find the total number of shortest paths that lead to endpoint B .

Option: 1

5200300


Option: 2

520300


Option: 3

520030


Option: 4

52030


Answers (1)

best_answer

We must take 12 steps to the right and 13 steps up in order to go for the shortest distance to endpoint B . Let x and y each represent a step to the right and an upward step, respectively. Consequently, there are 12 x steps and 13 y steps in total.

These 12 xs and 13 ys can be arranged in any way to find the shortest path. The binomial coefficient provides the number of possible arrangements for these steps:
{ }^n \mathrm{C}_r=\frac{n !}{r !(n-r) !}
where n denotes the overall number of steps, r the number of steps taken in one particular direction, in this case to the right, and \left ( n-r \right ) the number of steps taken in the opposite direction, in this case upwards.

Using this equation, we obtain:
\begin{aligned} & { }^{25} \mathrm{C}_{13}=\frac{25 !}{13 !(25-13) !} \\ = & \frac{25 !}{13 ! \times 12 !} \\ = & 5200300 \end{aligned}
Total number of ways : 5200300 . 

 

Posted by

Kuldeep Maurya

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