SUCCESS is a 7 letter word
the formula is given by
(total number of word)!/ repeat1! * repeat2 !
=7!/ 2!*2!
= 7*6*5*4*3*2/ 2*2
= 420
Hence answer E
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How many different strings of letters can be made by reordering the letters of the word SUCCESS?
S-3 C-2 U-1 E-1, total 7
Number of different strings = 7!/3!/2! = 420

IMO E
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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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Now let's calculate the number of arrangements of the letters in SUCCESS:
There are 7 letters in total
There are 3 identical S's
There are 2 identical C's
So, the total number of possible arrangements = 7!/[(3!)(2!)] = 420

Answer: E

Cheers,
Brent
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total ways ; SUCCESS ; 7!/2!*2!
solve 420
IMO E

Total letters =7

Repeated S's=3
Repeated C's =2

Total number of letters possible= \(\frac{7!}{(3!*2!)} =420\)

I guessed by selecting the only answer option that is a multiple of 7