Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

cinar Group Title

password question, need some help..

  • 2 years ago
  • 2 years ago

  • This Question is Closed
  1. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    • 2 years ago
    1 Attachment
  2. lopus Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    http://www.khanacademy.org/math/probability/v/probability-using-combinations

    • 2 years ago
  3. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    a) Let's try first by calculating the total number of passwords without requirements, and then subtracting the total number of passwords which DON'T meet the requirements.

    • 2 years ago
  4. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Cinar, can you do this?

    • 2 years ago
  5. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    62^10

    • 2 years ago
  6. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    that is total only..

    • 2 years ago
  7. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Now how many don't meet the 'at least one digit' rule, how many don't meet the 'at least one lower case letter', and how many don't meet the 'at least one upper case letter' requirement?

    • 2 years ago
  8. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    10^52+10^36+10^36

    • 2 years ago
  9. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    listen I'll be right back ok, give me couple minutes, I need to do something..

    • 2 years ago
  10. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    \( (26 +26)^{10}\) Have no digit \( (26+10)^{10} \) Have no lower case \((26+10)^{10} \) Have no upper case

    • 2 years ago
  11. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    We still double count the ones who break two or more rules, so we have to get rid of them. \(10^{10} \) break both upper and lower case rule \(26^{10} \) break both upper case and digit rule \(26^{10} \) break both lower case and digit rule \(0\) break all three rules, because it must contain at least a digit or letter

    • 2 years ago
  12. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    you'are right, I made a typo..

    • 2 years ago
  13. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    So we have \((10+26+26)^{10} - ((10+26)^{10} + (10+26)^{10} + (26+26)^{10} - (10^{10} + 26^{10} + 26^{10})) \)

    • 2 years ago
  14. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Do you understand how I did that?

    • 2 years ago
  15. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    hold on..

    • 2 years ago
  16. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    it is like union of three set..

    • 2 years ago
  17. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Yeah

    • 2 years ago
  18. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Are you doing probability with set theory?

    • 2 years ago
  19. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Discreet math?

    • 2 years ago
  20. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    Discreet math

    • 2 years ago
  21. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    So do you or don't you understand how I got what I got?

    • 2 years ago
  22. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    so, AUBUC=A+B+C-AIB-AIC-BIC+AIBIC I=intersection

    • 2 years ago
  23. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Yeah

    • 2 years ago
  24. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    got it..

    • 2 years ago
  25. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    how about part b, any idea..

    • 2 years ago
  26. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Do you have any ideas where to start?

    • 2 years ago
  27. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    let see

    • 2 years ago
  28. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    preceded by a letter means a1 or 1a

    • 2 years ago
  29. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I am confused..

    • 2 years ago
  30. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    I'm pretty sure it means a1

    • 2 years ago
  31. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    hmm, then password cannot be begun by a number..

    • 2 years ago
  32. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Well, one thing to ask is, must all digits be preceded by a number, or just at least one digit?

    • 2 years ago
  33. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    and also no number is successive

    • 2 years ago
  34. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    22 or 555 not allowed

    • 2 years ago
  35. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    a2ddd3y8jj8i898 is ok

    • 2 years ago
  36. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    I think a123456789 is also okay, because it has one digit immediately preceded by a letter. They didn't say ALL must follow the rule, just one.

    • 2 years ago
  37. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    so 1a23456789 would be ok too.

    • 2 years ago
  38. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    that' why I am confused..

    • 2 years ago
  39. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    listen I need some break to eat something..

    • 2 years ago
  40. cinar Group Title
    Best Response
    You've already chosen the best response.
    Medals 0

    I am back..

    • 2 years ago
  41. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    Ok. So one thing we can take into consideration is that for a password to have a digit and be invalid, it would have to have to be 1... 11.... 111.... basically a bunch of digits in order with no letters in between.

    • 2 years ago
  42. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    So one way is 1 digit and then 9 letters, with at least one capital and one lowercase

    • 2 years ago
  43. wio Group Title
    Best Response
    You've already chosen the best response.
    Medals 1

    So find how many ways we can have a password that is valid in (a) and not valid in (b) and subtract that from (a)

    • 2 years ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.