Question

    The average rainfall over a certain number of days was

    24 mm. On the next day, the rainfall was 60 mm and the average increased by 2 mm. Find the total rainfall before that day.
    A 408 Correct Answer Incorrect Answer
    B 400 Correct Answer Incorrect Answer
    C 420 Correct Answer Incorrect Answer
    D 430 Correct Answer Incorrect Answer
    E 390 Correct Answer Incorrect Answer

    Solution

    Let the number of days before be 'P'.

    Rainfall before = 24P

    (24P + 60) / (P + 1) = 26
    => 24P + 60 = 26P + 26
    => 2P = 34 => P = 17

    Total rainfall = 24 × 17 = 408 mm

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