ratio of blue marbles to red marbles is11:9 if there are 99 blue marbles how many red marbles

Question

ratio of blue to red marbles

Answer 1

Another way to think about this is:

11 blue marbles = 9 red marbles

So, 1 blue marble = 9/11 red marble

(99 blue) x (9/11 red per blue) = 81 red marbles

 

Answer 2

11     99     <-- Blue Marbles--  = --9      x      <-- Red Marbles

You can cross multiply to solve for x.

11*x = 99*9

11x = 891

11/11 x = 891/11

x = 81

So if there are 99 blue marbles, to maintain the ratio, there must also be 81 red marbles.