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    help Please ! i have the answer, it's 16%, but can you explain how we arrive to this this conclusion ? here is the question ; If a student's grade is 65 where the mean is 55 and the standard deviation 10, then the proportion of student who will score higher than 65 is about : a)34% b)68% c)16% d)2,5%





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    (Original post by Sashare)
    help Please ! i have the answer, it's 16%, but can you explain how we arrive to this this conclusion ? here is the question ; If a student's grade is 65 where the mean is 55 and the standard deviation 10, then the proportion of student who will score higher than 65 is about : a)34% b)68% c)16% d)2,5%
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    Let X denote the score of a student.

    P(X\leq65) = P(z\leq\frac{65-55}{10})

     = P(z\leq1) = 0.84

    Therefore P(X>65) = ...
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    (Original post by Sashare)
    help Please ! i have the answer, it's 16%, but can you explain how we arrive to this this conclusion ? here is the question ; If a student's grade is 65 where the mean is 55 and the standard deviation 10, then the proportion of student who will score higher than 65 is about : a)34% b)68% c)16% d)2,5%





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    Posted from TSR Mobile
    If you know that the distribution is Normal (or can assume this) you should know a standard result that says that about 68% of the distribution lies within 1 standard deviation of the mean.
 
 
 
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