The petrol tank of Jeremy's car was 60% empty. He went to the petrol kiosk and topped up 30 ℓ of petrol. When he reached the bank, the petrol tank was 95% full. Given that he used 8 ℓ of fuel to get to the bank from the kiosk, find the capacity of the petrol tank.
| |
Full |
Empty |
Total |
| Before |
2x4 =
8 u |
3x4 =
12 u |
5x4 =
20 u |
| Change 1 |
+ 30 |
- 30 |
|
| Change 2 |
- 8 |
+ 8 |
|
| After |
19x1 =
19 u |
1x1 =
1 u |
20x1 =
20 u |
60% =
60100 =
35 Empty : Total = 3 : 5
95% =
95100 =
1920 Full : Total = 19 : 20
The full capacity of the petrol tank is unchanged.
Make the totals the same. LCM of 5 and 20 is 20.
Volume of petrol in the end
= 8 u + 30 - 8
= 8 u + 22
19 u = 8 u + 22
19 u - 8 u = 22
11 u = 22
1 u = 22 ÷ 11 = 2
Capacity of the petrol tank
= 20 u
= 20 x 2
= 40 ℓ
Answer(s): 40 ℓ
