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Variations with Repetition (Quiz 3)

Variations with Repetition (Quiz 3)

Super Learner
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Hi 365 team and aspiring data scientists,
I have a quick Q about the quiz no 3 in the “Computing Variations with Repetition” module. 

 
Why is 8 to the power of 4 (8^4) not the correct answer? Can someone help me explain this? 
I would very much appreciate it.
 
Thank you,
Jimmy

Hey 365 team, can someone help with this query? I have been waiting for weeks now 🙁

4 days
1 Answer

Super Learner

Hi,
 
Try thinking about the quiz the following way:
 

  • How many different 4-letter codes are there so that each letter is one of the letters in the word “password”?

 
The “trick” here is that the word “password” has only 7 distinct letters: P, A, S, W, O, R, D. Therefore we need to arrange 4 out of 7 letters, allowing for repetition and their order is relevant (each 4-letter code is a unique code; the lock would not open if the code was PASW and you typed WASP). So you end up with:
 
V(n=7,p=4) = 7^4
 
Hope this helps!

Thanks a lot for this, Jacob! This finally clears my doubt 🙂 truly appreciate your effort.

3 days