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    Question

    The average of 10 numbers is 18. When two new numbers

    'a' and 'b' are added, the average increases by 2. If a - b = 30, find the value of b.
    A 15 Correct Answer Incorrect Answer
    B 13 Correct Answer Incorrect Answer
    C 10 Correct Answer Incorrect Answer
    D 25 Correct Answer Incorrect Answer

    Solution

    ATQ, Sum of 10 numbers = 10×18=180 Sum of 12 numbers = 12×20=240 So, a+b=240−180=60 ----------(i) And, a−b=30 -----------(ii) Solving (i) and (ii), we get: a+b=60 a−b=30 Adding these equations: 2a=90 a=45 Substituting a=45 into equation (i): 45+b=60 b=15

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