Answer
A tree diagram is the time consuming as you have to consider all the possible conditions of the combination but you can easily calculate the number of ways applying the formula of fundamental counting principle.
Work Step by Step
The total number of ways in which occurrence of series of successive things can be computed by multiplying the number of ways in which each thing may occur. This is called the fundamental counting principle.
Tree diagram gives you the clearer picture of the number of possibilities by considering all the possible conditions. It is useful for small calculations.
