Using diaries for many weeks, a study on the lifestyles of visually impaired students was conducted. The students kept track of many lifestyle variables including how many hours of sleep obtained on a typical day. Researchers found that visually impaired students averaged 9.38 hours of sleep, with a standard deviation of 1.63 hours. Assume that the number of hours of sleep for these visually impaired students is normally distributed. (a)  What is the probability that a visually impaired student gets less than 66 hours of sleep? (b)  What is the probability that a visually impaired student gets between 6.7and 7.79 hours of sleep? (c)  Fourty percent of students get less than how many hours of sleep on a typical day?

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Using diaries for many weeks, a study on the lifestyles of visually impaired students was conducted. The students kept track of many lifestyle variables including how many hours of sleep obtained on a typical day. Researchers found that visually impaired students averaged 9.38 hours of sleep, with a standard deviation of 1.63 hours. Assume that the number of hours of sleep for these visually impaired students is normally distributed.

(a)  What is the probability that a visually impaired student gets less than 66 hours of sleep?

(b)  What is the probability that a visually impaired student gets between 6.7and 7.79 hours of sleep?

(c)  Fourty percent of students get less than how many hours of sleep on a typical day?