A mixture P is formed by removing a certain amount of coffee from a co...
Every time 20% of the mixture is replace with a pure adulterant (here cocoa), the concentration of the mixture becomes 80% of the initial concentration.
Similarly when a proportion p of a mixture is replaced with pure adulterant, the concentration of the mixture becomes (1 - p) times the previous concentration. (0 ≤ p ≤ 1)
Initially there was pure coffee, so the strength of the mixture is 100% or 1 (in terms of proportion)
Let a proportion p of the mixture be replaced each time… Since after repeating the process twice, we have the concentration of coffee as
at the end of the two replacements.
Or, 20% of the mixture is replaced each time.
The ratio of cocoa powder in the mixture P and Q will then be
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A mixture P is formed by removing a certain amount of coffee from a co...
Understanding the Problem:
The problem involves two mixtures, P and Q, which are obtained by a process of replacing coffee with cocoa powder. We need to find the ratio of cocoa in mixture P to that in mixture Q.
Solution:
- Let the initial amount of coffee in the jar be C and the initial amount of cocoa be K.
- In mixture P, when the same amount of coffee is removed and replaced by cocoa powder, the ratio of coffee to cocoa remains the same as in the original mixture. Therefore, the ratio of coffee to cocoa in mixture P is C:K.
- In mixture Q, after the second replacement, the ratio of coffee to cocoa is given as 16:9.
- Since the amount of coffee and cocoa removed and added is the same in both P and Q, the ratio of coffee to cocoa in mixture Q is also C:K.
- From the given ratio 16:9, we can write C/K = 16/9.
- Now, we need to find the ratio of cocoa in mixture P to that in mixture Q, which would be K (cocoa in mixture P) / K (cocoa in mixture Q) = 9/16.
- Therefore, the ratio of cocoa in mixture P to that in mixture Q is 9:16, which is equivalent to 5:9.
Therefore, the correct answer is option C) 5:9.