3 sigma
Students' performance scores in a statistic test have a mean of 70 and a standard deviation of 4.0. The scores obtained can be modeled by a normal distribution. Find the probability that the score of a randomly selected student is
i. more than 80 marks
ii. less than 65 marks
Find also the number of students who scored above 80 marks if a total of 1200 students sat for the test.
i. more than 80 marks
ii. less than 65 marks
Find also the number of students who scored above 80 marks if a total of 1200 students sat for the test.
Correct answer:

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