Normal distribution & Probability
The grades of a group of 5000 students in an exam are normally distributed with a mean of 75 and a standard deviation of 5. A student from this group is selected randomly.
(i) Find the probability that his/her grade is greater than 90.
(ii) Find the probability that his/her grade is less than 50.
(iii) Find the probability that his/her grade is between 50 and 75.
(iv) Approximately, how many students have grades greater than 75.
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