The petrol tank of Julian's convertible was 60% empty. He went to the petrol station and topped up 36 ℓ of petrol. When he reached the school, the petrol tank was 85% full. Given that he used 9 ℓ of fuel to get to the school 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 |
+ 36 |
- 36 |
|
Change 2 |
- 9 |
+ 9 |
|
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 + 36 - 9
= 8 u + 27
17 u = 8 u + 27
17 u - 8 u = 27
9 u = 27
1 u = 27 ÷ 9 = 3
Capacity of the petrol tank
= 20 u
= 20 x 3
= 60 ℓ
Answer(s): 60 ℓ