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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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    1. It's strictly impossible to tell the answer without knowing how the scores are distributed, but here, it's clear that they are assuming a normal distribution

    2. For a normal distribution, roughly 68% of all values lie within 1 standard deviation from the mean - that means that 100%-68%=32% lie more than 1 standard deviation from the mean. You should now be able to figure out where 16% comes from. (Hint: values can be both lower and higher than the mean, and a normal distribution is symmetric about its mean)

    3. Minor point: It's "calculation", not "calcul"
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    This seems to be a duplicate post!
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    in a normal distribution there are about 68% of data within one standard deviation of the mean
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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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    You may have heard of the 68-95-99.7 rule, being approximately the percentage of normally-distributed random data within 1/2/3 standard deviations of the mean.
 
 
 
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