The petrol tank of Oscar's van was 60% empty. He went to the petrol station and topped up 28 ℓ of petrol. When he reached the hypermart, the petrol tank was 85% full. Given that he used 10 ℓ of fuel to get to the hypermart from the kiosk, find the capacity of the petrol tank.
|
Full |
Empty |
Total |
Before |
2x4 = 8 u |
3x4 = 12 u |
5x4 = 20 u |
Change 1 |
+ 28 |
- 28 |
|
Change 2 |
- 10 |
+ 10 |
|
After |
17x1 = 17 u |
3x1 = 3 u |
20x1 = 20 u |
60% =
60100 =
35 Empty : Total = 3 : 5
85% =
85100 =
1720 Full : Total = 17 : 20
The full capacity of the petrol tank is unchanged.
Make the totals the same. LCM of 5 and 20 is 20.
Volume of petrol in the end
= 8 u + 28 - 10
= 8 u + 18
17 u = 8 u + 18
17 u - 8 u = 18
9 u = 18
1 u = 18 ÷ 9 = 2
Capacity of the petrol tank
= 20 u
= 20 x 2
= 40 ℓ
Answer(s): 40 ℓ