Bunuel
How many arrangements of the letters of the word PARRAMATTA are possible?
A. 18,900
B. 37,800
C. 75,600
D. 151,200
E. 907,200
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When we want to arrange a group of items in which some of the items are identical, we can use something called the MISSISSIPPI rule. It goes like this:
If there are n objects where A of them are alike, another B of them are alike, another C of them are alike, and so on, then the total number of possible arrangements = n!/[(A!)(B!)(C!)....] So, for example, we can calculate the number of arrangements of the letters in MISSISSIPPI as follows:
There are
11 letters in total
There are
4 identical I's
There are
4 identical S's
There are
2 identical P's
So, the total number of possible arrangements =
11!/[(
4!)(
4!)(
2!)]
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Likewise, we can calculate the number of arrangements of the letters in PARRAMATTA:
There are
10 letters in total
There are
2 identical R's
There are
2 identical T's
There are
4 identical A's
So, the total number of possible arrangements =
10!/[(
2!)(
2!)(
4!)
= 37,800
Answer: B