Q1 A research suggests that college students should sleep 7 hours a day so that they could be energetic during daytime. Sleeping hours of college students in US. have normally distributed with a mean of 7.2 and standard deviation of 4. a) What is the probability that a randomly picked American college student's sleeping hours lower than 6.5? b) What is the probability that a randomly American college student's sleeping hours between 7.5 and 8.5? c) Ryan's sleeping hour is at the 70'\" percentile. How many hours he sleeps a clay