e.) 7.) A random sample of students was asked for the number of semester hours they are taking this semester. The standard deviation was found to be or = 3.1 semester hours. a.) How many students should be included in the sample to be 90% sure that the sample mean 7 is within 2 semester hours of the population mean ,u for all students at this college? (6 points) What percentage of college students owns a cellular phone? Let p be the proportion of college students that owns a cellular phone. a.) If no preliminary study is made to estimate p, how large a sample is needed to be 95% sure that a point estimate ,5\": will be within a distance of 0.06 from p? (6 points) b.) A preliminary study shows that approximately 72% of college students own cellular phones. How large a sample is needed to be 95% sure that a point estimate ,6 will be within a distance of 0.06 from p? (6 points)