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    Question

    Bowl 'P' initially holds 'a' liters of pure petrol.

    First, 25% of the petrol is removed and replaced with an equal amount of diesel. Subsequently, 40 liters of this mixture is removed, after which the remaining mixture contains 65 liters of diesel. Calculate the initial value of 'a'.
    A 140 Correct Answer Incorrect Answer
    B 190 Correct Answer Incorrect Answer
    C 155 Correct Answer Incorrect Answer
    D 175 Correct Answer Incorrect Answer
    E none of these Correct Answer Incorrect Answer

    Solution

    ATQ, we can find the final quantity of the milk in the resultant mixture by using the formula Final quantity of milk = X{1 – (b/X)}t, where X = initial quantity of milk, b = quantity of milk/mixture replaced and t = number of times the process is repeated. Therefore, a{1 – (0.25a/a)}{1 – (40/a)} = a – 65 Or, 0.75(a – 40) = a – 65 Or, a – 0.75a = 65 – 30 Or, a = 35/0.25 = 140

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