The petrol tank of Valen's lorry was 55% empty. He went to the petrol station and topped up 30 ℓ of petrol. When he reached the mall, the petrol tank was 80% full. Given that he used 9 ℓ of fuel to get to the mall from the kiosk, find the capacity of the petrol tank.
| |
Full |
Empty |
Total |
| Before |
9x1 =
9 u |
11x1 =
11 u |
20x1 =
20 u |
| Change 1 |
+ 30 |
- 30 |
|
| Change 2 |
- 9 |
+ 9 |
|
| After |
4x4 =
16 u |
1x4 =
4 u |
5x4 =
20 u |
55% =
55100 =
1120 Empty : Total = 11 : 20
80% =
80100 =
45 Full : Total = 4 : 5
The full capacity of the petrol tank is unchanged.
Make the totals the same. LCM of 20 and 5 is 20.
Volume of petrol in the end
= 9 u + 30 - 9
= 9 u + 21
16 u = 9 u + 21
16 u - 9 u = 21
7 u = 21
1 u = 21 ÷ 7 = 3
Capacity of the petrol tank
= 20 u
= 20 x 3
= 60 ℓ
Answer(s): 60 ℓ
