Risa has 2 tanks. Tank L and Tank M are of different capacities. If Tank L is filled by a tap at a rate of 3 litres per minute and Tank M is filled by a tap at a rate of 7 litres per minute, when Tank L is completely filled, 7 litres of water flowed out from Tank M. If Tank L is filled by a tap at a rate of 5 litres per minute and Tank M is filled by a tap at a rate of 2 litres per minute, when Tank L is completely filled, Tank M is only one-fifth-filled. What is the capacity of Tank M? Express your answer in litres.
|
Scenario 1 |
Scenario 2 |
Tank type |
Tank L |
Tank M |
Tank L |
Tank M |
Volume of the tank |
3 u |
7 u - 7 |
5 p |
2 p x 5 = 10 p |
Let 1 u be the time taken for Scenario 1.
Let 1 p be the time taken for Scenario 2.
3 u = 5 p --- (1)
7 u - 7 = 10 p
7 u = 10 p + 7 --- (2)
Make u the same.
(1) x 7
21 u = 35 p --- (3)
(2) x 3
21 u = 30 p + 21 --- (4)
(3) = (4)
35 p = 30 p + 21
35 p - 30 p = 21
5 p = 21
1 p = 21 ÷ 5 = 4.2
Volume of Tank M
= 10 p
= 10 x 4.2
= 42 ℓ
Answer(s): 42 ℓ