Subject

    গাণিতিক যুক্তি

    Topic

    ভগ্নাংশ

    A school has 10 classes with the same number of students in each class. One day, the weather was bad and many students were absent. 3 classes were halffull, 5 classes were ¾  full and 2 classes were 1/6 empty. A total of 74 students were absent. What is the total number of students in this school?

    ক)
    200
    খ)
    220
    গ)
    240
    ঘ)
    400

    Explanation

    Let NN be the total number of students in the school, and xx be the number of students in each class. Thus, N=10xN = 10x. The number of absent students is calculated based on the fraction of students present in each group: \begin{itemize} \item 3 classes were half-full (1/2 present, so 1/2 absent): 3×(x/2)3 \times (x/2) absent. \item 5 classes were 3/43/4 full (1/4 absent): 5×(x/4)5 \times (x/4) absent. \item 2 classes were 1/61/6 empty (1/6 absent): 2×(x/6)2 \times (x/6) absent. \end{itemize} Total absent students: (3x/2)+(5x/4)+(2x/6)=74(3x/2) + (5x/4) + (2x/6) = 74. Finding a common denominator (12): (18x/12)+(15x/12)+(4x/12)=74(18x/12) + (15x/12) + (4x/12) = 74. (18+15+4)x/12=74  ⟹  37x/12=74(18 + 15 + 4)x / 12 = 74 \implies 37x/12 = 74. Solving for xx: x=(74×12)/37=2×12=24x = (74 \times 12) / 37 = 2 \times 12 = 24. The total number of students N=10x=10×24=240N = 10x = 10 \times 24 = 240. The correct answer is 240\text{240} because setting up the equation based on the fractions of absent students for each group leads directly to x=24x=24 students per class, resulting in a total of 10x=24010x=240.

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