The petrol tank of Bryan's sports car was 70% empty. He went to the petrol kiosk and topped up 27 ℓ of petrol. When he reached the mall, the petrol tank was 85% full. Given that he used 5 ℓ of fuel to get to the mall from the kiosk, find the capacity of the petrol tank.
|
Full |
Empty |
Total |
Before |
3x2 = 6 u |
7x2 = 14 u |
10x2 = 20 u |
Change 1 |
+ 27 |
- 27 |
|
Change 2 |
- 5 |
+ 5 |
|
After |
17x1 = 17 u |
3x1 = 3 u |
20x1 = 20 u |
70% =
70100 =
710 Empty : Total = 7 : 10
85% =
85100 =
1720 Full : Total = 17 : 20
The full capacity of the petrol tank is unchanged.
Make the totals the same. LCM of 10 and 20 is 20.
Volume of petrol in the end
= 6 u + 27 - 5
= 6 u + 22
17 u = 6 u + 22
17 u - 6 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