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anonymous

  • one year ago

The time required to finish a test in normally distributed with a mean of 40 minutes and a standard deviation of 8 minutes. What is the probability that a student chosen at random will finish the test in more than 56 minutes? 84% 2% 34% 16%

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  1. amistre64
    • one year ago
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    what do you have to find a solution with?

  2. amistre64
    • one year ago
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    do you know the empirical rule?

  3. anonymous
    • one year ago
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    no I don't know it

  4. amistre64
    • one year ago
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    you have some studying to do then .... look up the empirical rule and let me know what you get

  5. anonymous
    • one year ago
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    okay I looked it up

  6. amistre64
    • one year ago
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    what does it say ...

  7. anonymous
    • one year ago
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    In statistics, the so-called 68–95–99.7 rule is a shorthand used to remember the percentage of values that lie within a band around the mean in a normal distribution with a width of one, two and three standard deviations, respectively; more accurately, 68.27%, 95.45% and 99.73% of the values lie within one, two and three standard deviations of the mean, respectively. In mathematical notation, these facts can be expressed as follows, where x is an observation from a normally distributed random variable, μ is the mean of the distribution, and σ is its standard deviation:

  8. amistre64
    • one year ago
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    copy paste eh, at least you found it :) now, we need to know how many standard deviation are between the mean, and the desired value. we start by finding the difference between them. what is the difference?

  9. anonymous
    • one year ago
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    I got it form here, I just need to know how to start it out. Thank you so much for your help!

  10. amistre64
    • one year ago
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    ok, if you need more help on it, just let me know.

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