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    A milk vendor has 50 L of milk and supplies 5 L to every customer. After each transaction he adds 5L of water. What is the percentage of milk containe
    Question

    A milk vendor has 50 L of milk and supplies 5 L to every customer. After each transaction he adds 5L of water. What is the percentage of milk contained in a litre of solution purchased by the fifth customer?

    A.

    65.6%

    B.

    72.9%

    C.

    83.1%

    D.

    59.4%

    Correct option is A


    Given:
    · Initial milk = 50 L
    · Supplies 5 L to each customer
    · After each customer, adds 5 L of water
    · We need milk % in 1 litre of solution bought by 5th customer
    Concept Used:
    We treat this as a successive dilution problem. After each transaction:
    · 5 L of the current solution (milk + water) is removed
    · Then 5 L of water is added
    We repeatedly remove a fraction of milk, since water doesn't affect milk amount directly.
    Solution:
    Step-by-step calculation:
    Initial state:
    Milk = 50 L
    Water = 0 L
    Total = 50 L
    Milk fraction = 1
    After 1st customer:
    Removed 5 L milk (since it's pure milk)
    Remaining milk = 45 L
    Add 5 L water → Total = 50 L
    Milk fraction = 45 / 50 = 0.9
    After 2nd customer:
    Removed 5 L × 0.9 = 4.5 L milk
    Remaining milk = 45 – 4.5 = 40.5 L
    Add 5 L water → Total = 50 L
    Milk fraction = 40.5 / 50 = 0.81
    After 3rd customer:
    Removed 5 L × 0.81 = 4.05 L milk
    Remaining milk = 40.5 – 4.05 = 36.45 L
    Add 5 L water → Total = 50 L
    Milk fraction = 36.45 / 50 = 0.729
    After 4th customer:
    Removed 5 L × 0.729 = 3.645 L milk
    Remaining milk = 36.45 – 3.645 = 32.805 L
    Add 5 L water → Total = 50 L
    Milk fraction = 32.805 / 50 = 0.6561
    5th customer:
    Milk in 1 L = 0.6561 L
    Percentage of milk = 0.6561 × 100 = 65.6%
    Final Answer: (a) 65.6%

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