Posted by **Adam** on Saturday, February 26, 2011 at 11:33pm.

It is known that an exam scores of students in STAT 2507 follow a normal distribution with a mean

of 70% and a standard deviation of 9%.

(A) If a student must obtain a mark of 50% to pass the exam, what proportion of students fail the exam?

(B) What is the probability that a randomly selected student will score between 65% and 85%?

(C) What is the minimum score required for a student to be in the top 10 percent of the class?

(D) What is the probability that a student will get exactly 70%?

- statistics and probability -
**drwls**, Sunday, February 27, 2011 at 12:44am
Familiarize yourself with a normal distribution table or online calculator, such as the one at

http://stattrek.com/Tables/Normal.aspx

(A) 1.3%

(B) Subtract P(x<65) from P(x<85)

(C) Find the value of X for which P(x<X) = 0.90 I get 81.5%

(D) Take the difference between getting a score of 70.5% and 69.5%

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