The petrol tank of George's car was 60% empty. He went to the petrol station and topped up 30 ℓ of petrol. When he reached the boutique, the petrol tank was 90% full. Given that he used 10 ℓ of fuel to get to the boutique from the kiosk, find the capacity of the petrol tank.
| |
Full |
Empty |
Total |
| Before |
2x2 =
4 u |
3x2 =
6 u |
5x2 =
10 u |
| Change 1 |
+ 30 |
- 30 |
|
| Change 2 |
- 10 |
+ 10 |
|
| After |
9x1 =
9 u |
1x1 =
1 u |
10x1 =
10 u |
60% =
60100 =
35 Empty : Total = 3 : 5
90% =
90100 =
910 Full : Total = 9 : 10
The full capacity of the petrol tank is unchanged.
Make the totals the same. LCM of 5 and 10 is 10.
Volume of petrol in the end
= 4 u + 30 - 10
= 4 u + 20
9 u = 4 u + 20
9 u - 4 u = 20
5 u = 20
1 u = 20 ÷ 5 = 4
Capacity of the petrol tank
= 10 u
= 10 x 4
= 40 ℓ
Answer(s): 40 ℓ
