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Statistics(probability) help

Former MemberFormer Member Posts: 1,876,324 The Mix Honorary Guru
Hi

I'm completely stuck on the probability theory of statistics. Anyone who may be able to help with these two questions would really do me a favor right now, I can see this being a very late night...

I have two components, A and B, the probability of A failing is 0.01, the probability of B failing is 0.02, and both components failing is 0.001. The questions asks does a failure in one component increase or decrease the likelyhood of the other component failing?

See I have used conditional probability to say that:
B fails given A does not fail and:
B fails given that A fails.

I get 0.02 for each using the formula though. Does anyone have a suggestion?

Comments

  • Former MemberFormer Member Posts: 1,876,324 The Mix Honorary Guru
    I know that smoking is the leading cause of statistics :D
  • Former MemberFormer Member Posts: 1,876,324 The Mix Honorary Guru
    I know 8 out of 10 cats prefer Whiskas :D
  • Former MemberFormer Member Posts: 1,876,324 The Mix Honorary Guru
    Erm well if those figures are the chance of something failing on it's own...

    If A fails -->

    0.01

    Then to get to the combined failing thing the chance of B failing now must be 0.1 (so 0.01 * 0.1 = 0.001). Initially it was 0.02, so we can see the chance of it failing after A fails has increased (by a factor of 5 I think)

    If B fails -->

    0.02

    to reach the figure then of 0.001, the new chance of A failing must be 0.05 (0.02 * 0.05 = 0.001). This is also greater than the original chance of 0.01. (again, by a factor of 5)

    So in both cases, if one component fails it increases the chance of the other component failing.

    I reckon anyway, I might be wrong :p
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