A bottle contains 20 litres of liquid A. 4 litres of liquid A is taken...
Given:
- A bottle contains 20 litres of liquid A.
- 4 litres of liquid A is taken out of it and replaced by the same quantity of liquid B.
- 4 litre of the mixture is taken out and replaced by the same quantity of liquid B.
To find: The ratio of the quantity of liquid A to that of liquid B in the final mixture.
Solution:
Let's assume that after n operations of replacement, the amount of liquid A left in the bottle is Aₙ and liquid B is Bₙ.
After the first operation of replacement:
- Quantity of liquid A left in the bottle = A₁ = 20 - 4 + 4×(B/A)
- Quantity of liquid B in the bottle = B₁ = 4
After the second operation of replacement:
- Quantity of liquid A left in the bottle = A₂ = A₁ - 4 + 4×(B/A)
- Quantity of liquid B in the bottle = B₂ = 4×(B/A)
We can write A₂ in terms of A₁ as follows:
A₂ = A₁ - 4 + 4×(B/A)
A₂ = (20 - 4 + 4×(B/A)) - 4 + 4×(B/A)
A₂ = A₁ - 4×(A/A) + 4×(B/A)
A₂ = A₁ + 4×(B/A) - 4
Similarly, we can write Bₙ in terms of A₁ as follows:
B₂ = 4×(B/A)
B₃ = 4×(B/A)×(B/A)
B₄ = 4×(B/A)×(B/A)×(B/A)
After n operations of replacement, we can write:
Aₙ = A₁ + 4×(B/A) - 4×(B/A)³
Bₙ = 4×(B/A)ⁿ
Substituting the values, we get:
Aₙ = 20×(1 - (1/5)³) + 4×(1 - (1/5)²)
Bₙ = 4×(1/5)ⁿ
Therefore, the ratio of the quantity of liquid A to that of liquid B in the final mixture is:
Aₙ:Bₙ = [20×(1 - (1/5)³) + 4×(1 - (1/5)²)]:[4×(1/5)ⁿ]
Aₙ:Bₙ = [16×(125/216) + 4×(16/25)]:[4×(1/5)ⁿ]
Aₙ:Bₙ = [100:27]:[1/5]ⁿ
Aₙ:Bₙ = 16:9 (n=2)
Therefore, the ratio of the quantity of liquid A to that of liquid B in the final mixture is 16:9.
A bottle contains 20 litres of liquid A. 4 litres of liquid A is taken...
1. Initially 20ltrs of Liquid A, 4ltrs of Liquid A is removed, remaining quantity of A is 20-4=16.
2. Now same quantity of Liquid B is added i.e 4ltrs, now A:B=16:4=4:1(4/5 parts of A) & (1/5 parts of B).
3. 4ltrs of total mixture is removed, A=16-(4/5*4)=16-16/5=64/5 &
B= 4-(1/5*4)=4-4/5=16/5
After removal of 4ltrs of mixture remaining quantities in A and B are 64/5 and 16/5.
4. Now same quantity of Liquid B is replaced i.e is 4ltrs = (16/5)+4= 36/5.
5. Ratio of A and B is A:B or A/B = (64/5):(36/5)=16:9.
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