The petrol tank of Fabian's convertible was 55% empty. He went to the petrol kiosk and topped up 20 ℓ of petrol. When he reached the temple, the petrol tank was 90% full. Given that he used 2 ℓ of fuel to get to the temple 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 |
+ 20 |
- 20 |
|
| Change 2 |
- 2 |
+ 2 |
|
| After |
9x2 =
18 u |
1x2 =
2 u |
10x2 =
20 u |
55% =
55100 =
1120 Empty : Total = 11 : 20
90% =
90100 =
910 Full : Total = 9 : 10
The full capacity of the petrol tank is unchanged.
Make the totals the same. LCM of 20 and 10 is 20.
Volume of petrol in the end
= 9 u + 20 - 2
= 9 u + 18
18 u = 9 u + 18
18 u - 9 u = 18
9 u = 18
1 u = 18 ÷ 9 = 2
Capacity of the petrol tank
= 20 u
= 20 x 2
= 40 ℓ
Answer(s): 40 ℓ
