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    Question

    The average score in Mathematics of 90 students of

    section A and B of class IX was 63. The number of students in A were 10 more than those in B. The average score of students in A was 30% more than that of students in B. The average score of students in B is:
    A 56 Correct Answer Incorrect Answer
    B 60 Correct Answer Incorrect Answer
    C 50 Correct Answer Incorrect Answer
    D 54 Correct Answer Incorrect Answer

    Solution

    Let the students in section B be ‘x’ Students in section A = x + 10 ⇒ (Sum of the score of students)/number of the students = 63 ⇒ Sum of the score of students = 90 × 63 ⇒ Sum of the score of students = 5670 Number of the students = 90 ⇒ x + x + 10 = 90 ⇒ x = 40 Students in Section B = 40 Students in section A = 40 + 10 = 50 Let the average be ‘p’. Average of students in section A = 130% of students in section B ⇒ (Average of students in section A/Average of students in section B) = 13p/10p ⇒ 13p × 50 + 10p × 40 = 5670 ⇒ 650p + 400p = 5670 ⇒ 1050p = 5670 ⇒ p = 5.4 Average of students in section B = 10p ⇒ 5.4 × 10 ⇒ 54

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