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!

Discrete probability distributions

  1. Mar 5, 2013 #1
    1. The problem statement, all variables and given/known data

    A certain manufacture advertises batteries that will run under a 75 amp discharge test for an average of 100 minutes, with standard deviation of 5 minutes.

    a. find an interval that must contain at least 90% of the performance periods fr batteries of this type.

    b. would you expect many batteries to die out in less than 80min why or why not?

    I solved a. to be (85,115)

    however i'm not quite sure what to do about B. I would guess and say that know due to the interval which is from 85 to 115 which would mean that the battery life generally last in that range however, i'm just speculating.


    Thanks

    Higgenz


    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Mar 5, 2013 #2

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    How many standard deviations would 80 min be from the average? Do you have any tables which tell you the percentage of a normal distribution that would be that far or further below the mean?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Discrete probability distributions
Loading...