The petrol tank of Oliver's bus was 70% empty. He went to the petrol station and topped up 41 ℓ of petrol. When he reached the school, the petrol tank was 85% full. Given that he used 8 ℓ of fuel to get to the school from the kiosk, find the capacity of the petrol tank.
| |
Full |
Empty |
Total |
| Before |
3x2 =
6 u |
7x2 =
14 u |
10x2 =
20 u |
| Change 1 |
+ 41 |
- 41 |
|
| Change 2 |
- 8 |
+ 8 |
|
| After |
17x1 =
17 u |
3x1 =
3 u |
20x1 =
20 u |
70% =
70100 =
710 Empty : Total = 7 : 10
85% =
85100 =
1720 Full : Total = 17 : 20
The full capacity of the petrol tank is unchanged.
Make the totals the same. LCM of 10 and 20 is 20.
Volume of petrol in the end
= 6 u + 41 - 8
= 6 u + 33
17 u = 6 u + 33
17 u - 6 u = 33
11 u = 33
1 u = 33 ÷ 11 = 3
Capacity of the petrol tank
= 20 u
= 20 x 3
= 60 ℓ
Answer(s): 60 ℓ
