Mrs. Hopkins has assigned a Study Island username using three letters for each of her students. No two letters can be duplicated in any one username.

Which of the following expressions could be used to determine the number of possible usernames?

Question

Mrs. Hopkins has assigned a Study Island username using three letters for each of her students. No two letters can be duplicated in any one username.

Which of the following expressions could be used to determine the number of possible usernames?

anonymous · Answer

A 26 × 3
B 3 × 26 × 25 × 24 
C 26 × 25 × 24

anonymous · Answer

Which Standard are you in? This is a permutations question..
Anyways

anonymous · Answer

what are you talking about?

anonymous · Answer

Acoording to the question no two same letters can be used..

Let us assume 3 blank spaces _ _ _

First space can be filled by any 26 of the alphabets in 26 ways>
Now since duplication isn't allowed, second space can be filled by the remaining 25 alphabets in 25 ways( Eg: If P has been used we can use any of the 26-1 (P) alphabets in the second place)

Similarly third place can be filled by 26-1-1=24 alphabets in 24 ways..

Therefore total ways= 26*25*24

Please don't copy the answer understand and ask if you've any queries. Don't mean to hurt you