The scores on a standardized test are Normal with mean = 50 and sd = 10.
a) What peoportion of scores falls less than 65?
b) What peoportion of scores falls between 40 to 65?
c) What is the 90the persentile of scores on the test?
[hint: changing your x values (test scores) to z values will make life easier!
recall that z = (test score  mean) / sd )
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1 answer

You can play around with Z table stuff at
davidmlane.com/hyperstat/z_table.html 👍
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answered by oobleck
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