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Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-23

  • question_answer
    The arithmetic mean of the scores of a group of students in a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25% a mean score of 31. The mean score of remaining 55% is

    A)  45%                

    B)  50%

    C)  51.4% (approx.)

    D)  54.6% (approx.)

    Correct Answer: C

    Solution :

    Let mean score of remaining 55% = x \[\,\,\,\,\,\,\,\,\,\,\,\,\,\,52=\frac{20\times 80+25\times 31+55\times x}{100}\] \[\Rightarrow \]\[5200=1600+775+55x\] \[\Rightarrow \]\[55x=5200-1600-775=2825\] \[\therefore \]\[x=\frac{2825}{55}=51.36=51.4%\](approx.)          


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