A ratio compares two quantities, expressing the relationship between an amount of one thing to an amount of another. For example, a ratio of 1:3 means that for every 1 of the first thing there are 3 of the second thing. To calculate the unknown quantity from a known ratio and one known amount, set up the ratio as a fraction and use algebra to solve. For example, if the ratio of hats to shirts is 2:3 and there are 20 hats, the number of shirts can be calculated as 30.

1. ACT Math
Ratios

2. What is a ratio?

3. A ratio means that for every amount of one
thing,

4. A ratio means that for every amount of one
thing,
1 hat

5. A ratio means that for every amount of one
thing,
there is an amount of another thing.
1 hat

6. A ratio means that for every amount of one
thing,
there is an amount of another thing.
1 hat
3 shirts

7. A ratio means that for every amount of one
thing,
there is an amount of another thing.
1 hat
3 shirts

8. Once again:
A ratio means that for every amount of one
thing,

9. A ratio means that for every amount of one
thing,
2 eggs

10. A ratio means that for every amount of one
thing,
there is an amount of another thing.
2 eggs

11. A ratio means that for every amount of one
thing,
there is an amount of another thing.
2 eggs
4 bacon

12. A ratio means that for every amount of one
thing,
there is an amount of another thing.
2 eggs
4 bacon

13. For example – if I say that the ratio between
Mormons and Catholics is 1:3

14. That means that for every sMormon
there are 3 Catholics.

15. That means that for every 1 Mormon
there are 3 Catholics.
1 LDS
=

16. That means that for every 1 Mormon
there are 3 Catholics.
1 LDS 1 2 3
Catholics=

17. If I say that the ratio between Mormons and
Catholics is 1:2

18. That means that for every 1 Mormon
there are 2 Catholics.

19. That means that for every 1 Mormon
there are 2 Catholics.
1 LDS
=

20. That means that for every 1 Mormon
there are 2 Catholics.
1 LDS 1
2
Catholics=

21. So, what does the ratio 3:4 between
copies of the Book of Mormon and
copies of the Bible mean?

22. So, what does the ratio 3:4 between
copies of the Book of Mormon and
copies of the Bible mean?
Answer?

23. So, what does the ratio 3:4 between
copies of the Book of Mormon and
copies of the Bible mean?
Answer:
For every three copies of the Book of Mormon

24. So, what does the ratio 3:4 between
copies of the Book of Mormon and
copies of the Bible mean?
Answer:
For every three copies of the Book of Mormon

25. So, what does the ratio 3:4 between
copies of the Book of Mormon and
copies of the Bible mean?
Answer:
For every three copies of the Book of Mormon
There are four copies of the Bible

26. If you know the ratio and the actual
amount of something you can find out
how much of the other thing there is.

27. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?

28. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
All you do is take the 2:3 and turn it into a
fraction:
2
3

29. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Then match the top ratio number (numerator)
with the actual number
2
3
20
x

30. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
And then the bottom number ratio (3) with it’s
number. But in this case we don’t know that
number so we put X
2
3
20
x

31. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
And then the bottom number ratio (3) with it’s
number. But in this case we don’t know that
number so we put X
2
3
20
x

32. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
And then the bottom number ratio (3) with it’s
number. But in this case we don’t know that
number so we put X
2
3
20
x
=

33. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Let’s use algebra to solve it:
2
3
20
x
=

34. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by X
2
3
20
x
=

35. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by X
2
3
20
x
=X* *X

36. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by X
2
3
20
x
=X*

37. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by X
2
3
20
x
=X

38. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by 3
2
3
20
x
=X3*

39. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by 3
2
3
20
x
=X3* *3

40. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by 3
2
3
20
x
=X3* *3

41. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by 3
2
3
20
x
=X *3

42. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Multiply both sides by 3
2
3
60
x
=X

43. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Divide both sides by 2
2
3
60
x
=X
2 2

44. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Divide both sides by 2
2
3
60
x
=X
2 2

45. If the ratio of hats to shirts is 2:3 and
there are 20 hats, how may shirts are
there?
Divide both sides by 2
3
30
x
=X

46. Let’s go back to the question

47. Let’s go back to the question
If the ratio of hats to shirts is 2:3 and there are 20
hats, how may shirts are there?

48. Let’s go back to the question
If the ratio of hats to shirts is 2:3 and there are 20
hats, how may shirts are there?
30 shirts