A bag contains yellow, green, blue, and white marbles. The ratio of yellow, green, blue, and white marbles is 1:2:3:4. If the bag contains 180 marbles, then how many blue marbles are there?
+1306 Let there be a number x such that multiplying each ratio by x gives the actual number of marbles there are of that color. We know 1x+2x+3x+4x=180, and we can simplify like terms to get 10x=180. Dividing by 10 gives x=18, so to find the number of blue marbles we multiply 3⋅18=54.
There are 54 blue marbles in the bag.
