Carcass wrote:
At least 15 percent of the students registered for Professor Tyler’s course dropped out before the end of the course. The drop-out rate for Professor Quin’s course was 20 percent greater than that for Professor Tyler’s course. If 120 students remained on the last day of Professor Quin’s class, which of the following could be the number of students who signed up for Professor Quin’s class?
Let X = Total number of students who signed up for Professor Quin’s class
Drop out rate of Quin's = 20% greater than than Tyler's rate
i.e Drop out rate of Quin's = 20% of 15
= 3 (That has to be greater than 15%)
= 18% (3+15)
According to the statement we have,
82% * X = 120 (since 18% dropped out, so 82 % remain in the last day)
or X = 146.34
So values above 146.34 are our answers.