1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Probability problem

  1. Oct 1, 2005 #1
    there is a pile of diodes. Half of them are checked. The pile is declared valid, if there are no more than 2% of broken diodes.

    Now i have to find the probability when having a pile of 100 diodes and 5% of them are broken, would be declared valid.

    How i did this task. there are 95 "ok" diodes and 5 broken diodes. The probability of this set of diodes declared valid is p(A)= (95C48*5C2 + 95C49*5C1 + 95C50*5C0)/100C50 which equals 0.5. The answer after the problem is said to be p(A)= 0,181
    Am I thinking wrong?
  2. jcsd
  3. Oct 1, 2005 #2


    User Avatar
    Science Advisor
    Homework Helper

    Perhaps as a check for your answer calculate the prob. of being declared "not valid." The two probs. should add to one.
  4. Oct 4, 2005 #3
    Pr(5% broken is declared ok/1/2 are checked)=Pr(you get either 0 broken or 1 broken in the pile of 50)

    =Pr(you get 0 or 1 faulty in 50/5 are faulty in 100)=50C5+50.50C4/{2*50C5+2*50C4*50+2*50C3*50C2}=0.1810892429
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Probability problem
  1. Probability problem (Replies: 2)

  2. Probability Problems (Replies: 1)

  3. Probability problem (Replies: 1)

  4. Probability problem (Replies: 1)