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anonymous

  • one year ago

Help with some normal distribution problems?

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  1. anonymous
    • one year ago
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    The time required to finish a test is normally distributed with a mean of 60 minutes and a standard deviation of 10 minutes. What is the probability that a student will finish the test in less than 70 minutes?

  2. sloppycanada
    • one year ago
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    Do you have a normal distribution chart in front of you?

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  3. anonymous
    • one year ago
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    yes

  4. sloppycanada
    • one year ago
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    So 60 is going to be that center little bit, excuse my terrible drawing. |dw:1435375646432:dw|

  5. sloppycanada
    • one year ago
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    A standard deviations is another line. Like this (but your graph is neater). Since each of the standard deviations is 10, All you care about is The line right after the mean and before. |dw:1435375698631:dw|

  6. anonymous
    • one year ago
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    So what's the probability that it will be less that 70 minutes

  7. sloppycanada
    • one year ago
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    Add all those percentages from 70% to 0.

  8. anonymous
    • one year ago
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    I got 69.1% is the correct?

  9. sloppycanada
    • one year ago
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    I got 69.2

  10. anonymous
    • one year ago
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    2. The time required to finish a test is normally distributed with a mean of 60 minutes and a standard deviation of 10 minutes What is the probability that a student will finish the test between 50 and 60 minutes?

  11. sloppycanada
    • one year ago
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    Same thing, So the standard deviation is 10. And you're looking at just between 50-60. your answer is the question mark. |dw:1435376877515:dw|

  12. anonymous
    • one year ago
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    Is the answer 34.1?

  13. sloppycanada
    • one year ago
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    Yes!

  14. anonymous
    • one year ago
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    The time required to finish a test is normally distributed with a mean of 60 minutes ad a standard deviation of 10 minutes. What is the Z-score for a student who finishes the test in 45 minutes?

  15. sloppycanada
    • one year ago
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    |dw:1435378336477:dw|

  16. anonymous
    • one year ago
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    I got -3/2 is the correct?

  17. sloppycanada
    • one year ago
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    Yeah, that's right.

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