SOLUTION: 1200 students took an examination. Their mean marks is 53. The standard deviation is 15. Assume Normal distribution of marks.If only 40% of the students are required to be promoted

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Question 986467: 1200 students took an examination. Their mean marks is 53. The standard deviation is 15. Assume Normal distribution of marks.If only 40% of the students are required to be promoted, what should be the marks for promotion?
Answer by stanbon(75887) About Me  (Show Source):
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1200 students took an examination. Their mean marks is 53. The standard deviation is 15. Assume Normal distribution of marks.If only 40% of the students are required to be promoted, what should be the marks for promotion?
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Find the z-value with a right tail of 40%
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invNorm(0.60) = 0.2534
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Find the corresponding mark value::
x = 0.2534*15+53
Ans:: x = 56.8
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Cheers,
Stan H.