1. Solving a rate problem

2. Solving a rate problem If gas is 66 cents per L, what is this in dollars per gallon?

3. If gas is 66 cents per L, what is this in dollars per gallon? In this problem we have two units: “ cents ” and “ gallons ”

4. If gas is 66 cents per L, what is this in dollars per gallon? We have to be able to turn the words “ 66 cents per liter ” into a term we can use in a calculation. 66centsper liter =

5. Now we can begin our calculation: We first write what we are given We will be changing both given units, cents and liters, in this problem

6. We will now change one unit at a time to the desired unit.

7. We will now change one unit at a time to the desired unit. Remember, we always multiply

8. We will now change one unit at a time to the desired unit. It does not matter which one we start with so we will start with liters.

9. We will now change one unit at a time to the desired unit. We start by writing liters on the top of the next term.

10. We will now change one unit at a time to the desired unit. We start by writing liters on the top of the next term.

11. We will now change one unit at a time to the desired unit. On the bottom we will place the units we want to replace for liters, qt.

12. Now we put quarts on the bottom

13. We put 1.08 in front of qt since 1l = 1.08 qt.

14. We have now converted liters into quarts.

15. Now we will convert quarts into gallons

16. We put qt on the top of the 3rd term

17. Now we will convert quarts into gallons Then we put gal on the bottom

18. Now we will convert quarts into gallons Now we are ready to put numbers in front of the units

20. Since we know that 1 gal = 4 qt., those are the numbers we place in front of those units

21. We are half way done. We have converted one of the units, liters, into gallons.

22. Now we will change cents into dollars We are half way done. We have converted one of the Units, liters, into gallons.

23. On the bottom of the 4th term we put the units “cents”

24. Cents on the bottom of the 4th term will factor out with cents on the top of the first term.

25. Dollars are the unit that we want to factor in.

26. So dollars go on top of the 4th term. =

27. = Now we need to put numbers in front of the units of the 4th term.

28. Now we need to put numbers in front of the units of the 4th term. We know that 1 dollar = 100 cents. So those are the appropriate numbers. =

29. When we factor the units we are left with dollars/gallon

30. Those are the units we want.

31. When we factor the units we are left with dollars/gallon Those are the units we want. Now we can “do the math”

32. When we do the math,

33. everything on the bottom gets divided,

34. When we do the math, everything on the bottom gets divided, and everything on top gets multiplied

35. When we do the math, into our calculator, we put 66 / 1.08 x 4 / 100

36. Our fewest number of significant digits is 2 from “66cents”, so we have only 2 digits in our answer 2.4 into our calculator, we put 66 / 1.08 x 4 / 100

37. Another way of showing our answer would be

38. This would be the same as saying 2.4 dollars per gallon.

39. If gas is 66 cents per L, what is this in dollars per gallon?