The petrol tank of Archie's sports car was 65% empty. He went to the petrol station and topped up 15 ℓ of petrol. When he reached the temple, the petrol tank was 70% full. Given that he used 1 ℓ of fuel to get to the temple from the kiosk, find the capacity of the petrol tank.
|
Full |
Empty |
Total |
Before |
7x1 = 7 u |
13x1 = 13 u |
20x1 = 20 u |
Change 1 |
+ 15 |
- 15 |
|
Change 2 |
- 1 |
+ 1 |
|
After |
7x2 = 14 u |
3x2 = 6 u |
10x2 = 20 u |
65% =
65100 =
1320 Empty : Total = 13 : 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
= 7 u + 15 - 1
= 7 u + 14
14 u = 7 u + 14
14 u - 7 u = 14
7 u = 14
1 u = 14 ÷ 7 = 2
Capacity of the petrol tank
= 20 u
= 20 x 2
= 40 ℓ
Answer(s): 40 ℓ