To answer the ratio, massage this equation around to find ' n/m ' . Let's subtract 'm' from each side: 4n = 2n + 7m Subtract '2n' from each side: 2n = 7m Divide each side by 'm' :2 (n/m) = 7 Divide each side by 2 : n/m = 7/2 . . . . . there's your ratio. That's choice-'e'.
There will be at least 1,350 bacteria in the Petri dish in 3 hours, or at 11:00am. 8:00am: 50 bacteria 9:00am: 150 bacteria 10:00am: 450 bacteria 11:00am: 1350 bacteria