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Average Questions Answers

  • 22. When a student weighing 45 kgs left a class, the average weight of the remaining 59 students increased by 200g. What is the average weight of the remaining 59 students

    1. 55
    2. 56
    3. 57
    4. 58
    Answer And Explanation

    Answer: Option C

    Explanation:

    Let the average weight of the 59 students be A.
    So the total weight of the 59 of them will be 59*A.

    The questions states that when the weight of this student who left is added, the total weight of the class = 59A + 45
    When this student is also included, the average weight decreases by 0.2 kgs

    \begin{aligned}
    \frac{59A + 45}{60} = A - 0.2
    \end{aligned}

    => 59A + 45 = 60A - 12
    => 45 + 12 = 60A - 59A
    => A = 57

  • 23. Marks of a student were wrongly entered in computer as 83, actual marks of that student were 63. Due to this mistake average marks of whole class got increased by half (1/2). Find the total number of students in that class.

    1. 25
    2. 30
    3. 35
    4. 40
    5. 45
    Answer And Explanation

    Answer: Option D

    Explanation:

    Suppose total number of students are = X
    \begin{aligned}
    Total increase = x*\frac{1}{2} = \frac{x}{2} \\
    => \frac{x}{2} = 83-63 = 20 \\
    => x = 40
    \end{aligned}