Cristine's middle school has a total of 900 students and 45 teachers. The local high school has 110 teachers and a student-teacher ratio proportional to the middle school's. How many students will Cristine find when she gets to high school? A) 900 B) 1100 C) 2200 D) 2500

Write and solve an equation of ratios:

900 students      45 teachers         
------------------  = -----------------  
          x               110 teachers     

Cross multiplying, we get (900)(110) / 45, or

                                                                 
so x = # of students in the high school = 2200   (answer)