The petrol tank of Tom's van was 60% empty. He went to the petrol kiosk and topped up 14 ℓ of petrol. When he reached the bakery, the petrol tank was 70% full. Given that he used 2 ℓ of fuel to get to the bakery 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 |
+ 14 |
- 14 |
|
| Change 2 |
- 2 |
+ 2 |
|
| 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 + 14 - 2
= 4 u + 12
7 u = 4 u + 12
7 u - 4 u = 12
3 u = 12
1 u = 12 ÷ 3 = 4
Capacity of the petrol tank
= 10 u
= 10 x 4
= 40 ℓ
Answer(s): 40 ℓ
