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mathmath333

  • one year ago

In the Suniti Building in Mumbai there are 12 floors plus the ground floor.9 people get into the lift of the building on the ground floor.The lift does not stop on the first floor. If 2,3 and 4 people alight from the lift on its upward journey,then in how many ways can they do so?(Assume they alight on different floors)

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  1. mathmath333
    • one year ago
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    \(\large \color{black}{\begin{align} & \normalsize \text{ In the Suniti Building in Mumbai there are 12 floors plus }\hspace{.33em}\\~\\ & \normalsize \text{ the ground floor.9 people get into the lift of the building }\hspace{.33em}\\~\\ & \normalsize \text{ on the ground floor.The lift does not stop on the first floor.}\hspace{.33em}\\~\\ & \normalsize \text{ If 2,3 and 4 people alight from the lift on its upward }\hspace{.33em}\\~\\ & \normalsize \text{ journey,then in how many ways can they do so?(Assume}\hspace{.33em}\\~\\ & \normalsize \text{ they alight on different floors)}\hspace{.33em}\\~\\ & a.)\ 11C3 \times 3P3 \hspace{.33em}\\~\\ & b.)\ 11P3 \times 9C4 \times 5C3 \hspace{.33em}\\~\\ & c.)\ 10P3 \times 9C4 \times 5C3 \hspace{.33em}\\~\\ & d.)\ 12C3 \hspace{.33em}\\~\\ \end{align}}\)

  2. anonymous
    • one year ago
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    We can select the three floors in 11P3 . Then of the 9 people four can leave in 9C4 ways Three of the remaining 5 can be selected in 5C3 ways so 11p3*9c4*5c3

  3. mathmath333
    • one year ago
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    I am having difficulty in interpreting the question

  4. anonymous
    • one year ago
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    well you see in 11P3 order is important

  5. anonymous
    • one year ago
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    in 9P3 order doesnt matter any way would be fine

  6. anonymous
    • one year ago
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    does that make sense ?

  7. anonymous
    • one year ago
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    see there is total of 13 floors 12+ ground floor

  8. mathmath333
    • one year ago
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    i know order is important in permutation and order isn't important in combination

  9. mathmath333
    • one year ago
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    11p3 where this come from ?

  10. anonymous
    • one year ago
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    i am coming to that

  11. anonymous
    • one year ago
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    because you see they are already on the ground level and they skip the first floor

  12. anonymous
    • one year ago
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    so 13 -2 =?

  13. mathmath333
    • one year ago
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    11 and 3 ?

  14. anonymous
    • one year ago
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    3 is no of ppl leaving the lift

  15. anonymous
    • one year ago
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    srry its not 3 ppl its 3 floors

  16. anonymous
    • one year ago
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    i was thinking about 5C3

  17. mathmath333
    • one year ago
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    ok and how come 9C4

  18. anonymous
    • one year ago
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    now selecting 4 ppl from 9 in 9C4

  19. mathmath333
    • one year ago
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    why r u selecting only 4 people

  20. anonymous
    • one year ago
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    ( if 2, 3 and 4 people alight from the lift)*

  21. anonymous
    • one year ago
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    now only 8 remaining so now selecting 3 from remaining 5 in 5C3

  22. anonymous
    • one year ago
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    ok in 11C3 , 11 floors and the reason i choose 3 floors because (2,3 and 4 ppl alight from the lift)

  23. dan815
    • one year ago
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    still need help?

  24. mathmath333
    • one year ago
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    yes

  25. mathmath333
    • one year ago
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    about 9C4 and 5C3

  26. dan815
    • one year ago
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    |dw:1442550398498:dw|

  27. dan815
    • one year ago
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    |dw:1442550724750:dw|

  28. dan815
    • one year ago
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    |dw:1442550796441:dw|

  29. dan815
    • one year ago
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    does it make sense

  30. dan815
    • one year ago
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    |dw:1442550935658:dw|

  31. dan815
    • one year ago
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    lets just go place my place, there are 4 spots and 9 people

  32. dan815
    • one year ago
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    |dw:1442550963765:dw|

  33. dan815
    • one year ago
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    9*8*7*6/4! = 9 choose 4

  34. dan815
    • one year ago
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    |dw:1442551022823:dw|

  35. mathmath333
    • one year ago
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    "lets just go place my place, there are 4 spots and 9 people" but where is given in que that their are 4 spots

  36. dan815
    • one year ago
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    2,3,4

  37. dan815
    • one year ago
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    is how they leave

  38. dan815
    • one year ago
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    you want to know the different groups of 2,3,4 that are possible

  39. mathmath333
    • one year ago
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    but 2,3,4 = 3 groups

  40. dan815
    • one year ago
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    yes but the 4 people that leave

  41. dan815
    • one year ago
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    which 4 people leave

  42. dan815
    • one year ago
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    people are not identical

  43. dan815
    • one year ago
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    from your 9 people there are 9 choose 4 ways of picking a group of 4 people that leave the elevator

  44. mathmath333
    • one year ago
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    ok

  45. mathmath333
    • one year ago
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    and 5c3

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