Exercise 7.8 gave the following probability distribution for x = the number of courses for which a randomly selected student at a certain university is registered:

For this probability distribution, ? = 4.66 and ? = 1.20.

a. Because ? - ? = 3.46, the x values 1, 2, and 3 are more than 1 standard deviation below the mean. What is the probability that x is more than 1 standard deviation below its mean? See Example 7.13.

b. What x values are more than 2 standard deviations away from the mean value (either less than ? - 2? or greater than ? + 2?)?

c. What is the probability that x is more than 2 standard deviations away from its mean value?

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1 2 3 4 5 6 7 p(x) 0.02 0.03 0.09 0.25 0.40 0.16 0.05