Question
A mixture contains 80% juice and rest water. A man
withdrew some mixture and replaced it with same quantity of kerosene, such that the quantity of juice remaining in the mixture now is 64%. If the man wants to bring down the quantity of juice to less than 41%, then how many more times should he repeat the same process?Solution
Let the percentage of mixture withdrawn first time be ‘p%’. ATQ; 80 × {1 − (p/100)} = 64 Or,
1 − (p/100) = 0.8 Or,
(p/100) = 0.2 So,
p = 20 So, 20% mixture is drawn every time. Now,
Quantity of juice remaining after withdrawing once more = 64 × 0.8 = 51.2 And,
Quantity of juice remaining after withdrawing once more = 51.2 × 0.8 = 40.96 So, after withdrawing two more times, the quantity of juice reaches less than 41%.
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