Question

    The average of five consecutive prime numbers is 11. Find

    the third number.
    A 11 Correct Answer Incorrect Answer
    B 23 Correct Answer Incorrect Answer
    C 28 Correct Answer Incorrect Answer
    D 30 Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the first prime number be 'x'

    Therefore, the five consecutive prime numbers will be 'x', (x + 2), (x + 4), (x + 6), (x + 8)

    ATQ:

    x + (x + 2) + (x + 4) + (x + 6) + (x + 8) = 5 × 11

    Or, 5x + 20 = 55

    Or, 5x = 55 - 20

    Or, 5x = 35

    Or, x = 35 ÷ 5 = 7

    Therefore, the first number = 7

    Third number = (x + 4) = 7 + 4 = 11

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