Quantcast

A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

samnatha

  • 2 years ago

help please !! if 20% of the balls produced by the machine are defective find the probability that out of the 4 balls selected at random (i) 2 are defective (ii) not more than 2 are defective i have done part (i) i got 0.1536 but i need help with part (ii)

  • This Question is Open
  1. amistre64
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    this might be better suited to a binomial setup

  2. samnatha
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    thats what i did for part i and i got that i'm just not sure what to do for the other part

  3. amistre64
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[P(2~out~of~4)=\binom{4}{2}~(bad)^2~(good)^2\] \[P(2~out~of~4)=6~(.20)^2~(.80)^2\]

  4. amistre64
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    the second part corresponds to an OR setup P(0) or P(1) or P(2)

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

    how do you do the second part i have done the first part ..i just need help with the second part

  6. amistre64
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[P(0,1,2~out~of~ 4)=6[(.2)^0 (.8)^4+(.2)^1 (.8)^3+(.2)^2 (.8)^2]\]

  7. samnatha
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    where did u get the six from ?

  8. amistre64
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    hmm, i do seem to have been a little amiss with that .... apparently we are not choosing 2 out of 4 each time :/ (4 0) = 1 (4 1) = 4 (4 2) = 6

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

    ok so i got 0.9728 for my final answer ?

  10. samnatha
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    is that right ?

  11. amistre64
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    that does seem about right. can you see any other errors in my remembering of this?

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

    nope although i wouldn't have added it up to 6 i would have done each sum seperatly and then added them but thank you for your help :)

  13. amistre64
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 1

    so the liklihood that no more than 2 are defective out of 4 is about 98%, sounds like a winner to me ... good luck :)

  14. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

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.