Could you please explain the question in the attchment for me? I read the answer

Question

Could you please explain the question in the attchment for me?
I read the answer, but dont understand.
When we divide by the factor of the number of undistinguished items, the idea is that the order is not important. But in this question, the order IS important, for you cannot shoot a target that is not at the bottom.
So...Could you please teach me?
Thank you!

Discrete and Combinatorial Mathematics (5th Edition Chapter 1.2, Problem 23E Bookmark Show all steps ON Problem Twelve clay targets (identical in shape) are arranged in four hanging columns, as shown in Fig There are four red targets in the first column, three white ones in the second column, two green targets in the third column, and three blue ones in the fourth column. To join her college drill team, Deborah must break all 12 of these targets (using her pistol and only 12 bullets) and in so doing must always break the existing target at the bottom of a column. Under these conditions, in how many different orders can Deborah shoot down (and break) the 12 targets? Figure

Explanation / Answer

Answer

The condition, ‘must always break the existing target at the bottom of a column’ implies that within a column, the shooter has no option and must shoot from bottom to top. Thus, the only option available is the order in which the shooter opts for the colour. Since there are 4 colours, these 4 colours can be ordered in 4! = 24 ways.

Hence, the answer is 24 ANSWER   

[going beyond: 24 orders are RWGB, RWBG, RGWB, RGBW, RBWG, RBGW …..

These 6 start with R. Similarly, there are 6 starting with each of W, G and B]

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