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?
The other guy gave the right answer, but, heck, you
could get that from the answers in the back of the book.
That doesn't help you with the "how" of solving the problem.
Here's the way I answered this problem several days ago.
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?
Consider: "The ratio of yellow, green, blue, and white marbles is 1:2:3:4."
Call the number of yellow marbles X.
So the number of green marbles is 2X.
And the number of blue marbles is 3X.
And the number of white marbles is 4X.
Add up all the marbles and you have 10X = 180
Therefore X = 18 yellow marbles
2X = 36 green marbles
3X = 54 blue marbles
4X = 72 white marbles
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