At an afterschool tutoring program, the ratio of teachers to students is 18 to 100. Which ratio is equivalent to the ratio of teachers to students?

A 1 to 18
B 9 to 50
C 4 to 25
D 6 to 20

Airline passengers arrive randomly and independently at the passenger-screening facility at a major international airport. the mean arrival rate is 10 passengers per minutes. compute the following probabilities. p(x = 4) p(x > 11)

The lines shown below are parallel. if the green line has a slope of -1, what is the slope of the red line?

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9