The petrol tank of Wesley's convertible was 55% empty. He went to the petrol station and topped up 19 ℓ of petrol. When he reached the church, the petrol tank was 70% full. Given that he used 4 ℓ of fuel to get to the church 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 |
+ 19 |
- 19 |
|
Change 2 |
- 4 |
+ 4 |
|
After |
7x2 = 14 u |
3x2 = 6 u |
10x2 = 20 u |
55% =
55100 =
1120 Empty : Total = 11 : 20
70% =
70100 =
710 Full : Total = 7 : 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 + 19 - 4
= 9 u + 15
14 u = 9 u + 15
14 u - 9 u = 15
5 u = 15
1 u = 15 ÷ 5 = 3
Capacity of the petrol tank
= 20 u
= 20 x 3
= 60 ℓ
Answer(s): 60 ℓ