The petrol tank of Bobby's convertible was 60% empty. He went to the petrol station and topped up 25 ℓ of petrol. When he reached the market, the petrol tank was 70% full. Given that he used 10 ℓ of fuel to get to the market 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 |
+ 25 |
- 25 |
|
| Change 2 |
- 10 |
+ 10 |
|
| After |
7x1 =
7 u |
3x1 =
3 u |
10x1 =
10 u |
60% =
60100 =
35 Empty : Total = 3 : 5
70% =
70100 =
710 Full : Total = 7 : 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 + 25 - 10
= 4 u + 15
7 u = 4 u + 15
7 u - 4 u = 15
3 u = 15
1 u = 15 ÷ 3 = 5
Capacity of the petrol tank
= 10 u
= 10 x 5
= 50 ℓ
Answer(s): 50 ℓ
