# Thread: "When a petrol tank is 7/12 full it contains 5 1/4 gallons."

1. ## "When a petrol tank is 7/12 full it contains 5 1/4 gallons."

I've been racking my brains how to solve this. Help, someone.
When a petrol tank is 7/12 full it contains 5 1/4 gallons. How many gallons does it hold when full?

2. What have your brain-rackings produced?

Maybe a Ratio or Proportion would help?

3. Originally Posted by MathsPlease
I've been racking my brains how to solve this. Help, someone.
When a petrol tank is 7/12 full it contains 5 1/4 gallons. How many gallons does it hold when full?
Since you posted this to "Arithmetic", I'll assume that you don't have any experience with "Pre-Algebra" or beyond. So:

You have tank that is 7/12 full. Draw seven boxes to correspond to this amount:

Code:
part-full tank:

*--*--*--*--*--*--*--*
|  |  |  |  |  |  |  |
*--*--*--*--*--*--*--*
You have 5 1/4 gallons in the part-full tank. When you convert this mixed number into an improper fraction, what do you get?

Then how many gallons (it'll be a fractional amount) is in each of the boxes above? (Hint: Divide by 7.)

How many boxes would indicate a completely full tank?

Then how many gallons would be in a completely full tank? (Hint: Multiply.)

If you get stuck, please reply showing your work in following the step-by-step instructions above. Thank you!

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