NIELIT Scientific Assistant A 2020 November: 19

Question

What is the total number of ways to reach from $A$ to $B$ in the network given?

• A. $12$
• B. $16$
• C. $20$
• D. $22$

Answer 1

Just trying to answer logically.
If you consider first node from A, there are 4 possible ways to reach B. So from A there are 4 nodes at level 1, which means total number of ways to reach B is 16.

Answer 2

From A $\rightarrow$ Level 1, we have 4 edges.

From Level 1 $\rightarrow$ Level 2, we can choose between 2 edges.

From Level 2 $\rightarrow$ Level 3, every vertex has 2 edges.

Applying Product Rule : $4\times 2\times 2 = 16$