Question 138510
The mean science achievement score of a group of Grade 8 students is 78 and 
s of 10.
 Granting that the scores of these students are normally distributed, how many would you expect to score less than 85?
Find the z-score of 85.
z(85)=(85-78)/10 = -0.7
P(0 < x < 85) = P(0 < z < -0.7) = 0.2580
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 If the number of students who took the test is 200, how many would that be? How many students would score more than 85?
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0.2580*200 = 51.6;rounding down you get 51 students scored below 85
200-51 = 149 students scored above 85
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Cheers,
Stan H.