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9th Class Mathematics Statistics Question Bank Statistics

  • question_answer
    The mean age of 20 students of a class is 10 years. If the age of their teacher is also included then the mean is increased by one year. The age of teacher is

    A)  21 years   

    B)           41 years

    C)  31 years         

    D)  None of these

    Correct Answer: C

    Solution :

         Total age of 20 students\[=10\times 20=200.\] Mean age of 20 students and the teacher = 11 years. i.e., total age of 20 students and the teacher \[=21\times 11=231\]years Hence, age of teacher\[=231-200=31\]years


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