7 tanks and 6 pails can hold 74.7 litres of water.
1 tank and 1 pail can hold 11.2 litres of water.
- How many litres of water can 1 tank hold?
- How many litres of water can 1 pail hold?
- How many litres of water can 8 pails hold?
- How many litres of water can 7 pails and 7 tanks?
(a)
7 tanks + 6 pails = 74.7 --- (1)
1 tank + 1 pail = 11.2 --- (2)
(2) x 6
1 tank + 1 pail = 11.2
6 tanks + 6 pails = 11.2 x 6
6 tanks + 6 pails = 67.2 --- (3)
(1) - (3)
(7 tanks + 6 pails) - (6 tanks + 6 pails) = 74.7 - 67.2
7 tanks + 6 pails - 6 tanks - 6 pails = 7.5
7 tanks - 6 tanks + 6 pails - 6 pails = 7.5
1 tank = 7.5
Volume of 1 tank = 7.5 ℓ
(b)
Substitute 1 tank = 7.5 into (2).
1 tank + 1 pail = 11.2
7.5 + 1 pail = 11.2
1 pail = 11.2 - 7.5 = 3.7
Volume of 1 pail = 3.7 ℓ
(c)
Volume of 8 pails
= 8 x 3.7
= 29.6 ℓ
(d)
Volume of 7 pails and 7 tanks
= 7 x 3.7 + 7 x 7.5
= 25.9 + 52.5
= 78.4 ℓ
Answer(s): (a) 7.5 ℓ; (b) 3.7 ℓ; (c) 29.6 ℓ; (d) 78.4 ℓ