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# The grades of a group of 1000 students in an exam are normally distributed with a mean of 70 and a standard deviation of 10. A student from this...

The grades of a group of 1000 students in an exam are normally distributed with a mean of 70 and a standard deviation of 10. A student from this group is selected randomly.

a) Find the probability that his/her grade is greater than 80.

b) Find the probability that his/her grade is less than 50.

c) Find the probability that his/her grade is between 50 and 80.

d) Approximately, how many students have grades greater than 80?