The third group of numbers, 8-11 hours of sleep, begins in 8, making it the minumum number group that we can use. The second eligigble group is 12-15 hours because it garuntees at least 12 hours of sleep. When add the 8 students who sleep for 8-11 hours to the 2 students who sleep 12-15 hours, we get 10 students who sleep 8+ hours frequently.
