Cara has 60 marbles in a bag. 20 of them are yellow, half as many are green, and the remaining marbles are equally divided between red and blue. If Cara picks a marble at random, what are the odds it's blue (expressed as a percentage)? Let's think first. Chain of thought:
First find the number of green marbles: 20 yellow marbles / 2 = 10 green marbles. Then find how many marbles are either red or blue: 60 marbles - 20 yellow marbles - 10 green marbles = 30 marbles. Divide this number in half to find how many marbles are blue: 30 marbles / 2 = 15 blue marbles. Finally, divide the number of blue marbles by the total number of marbles and multiply by 100 to find the percentage chance of getting a blue marble: 15 marbles / 60 marbles * 100 = 25%.
Therefore, the answer is 25.