JEE Main & Advanced Mathematics Statistics Question Bank Mean

  • question_answer
    If the values \[1,\,\frac{1}{2},\,\frac{1}{3},\,\frac{1}{4},\,\frac{1}{5},\,.....,\frac{1}{n}\] occur at frequencies 1, 2, 3, 4, 5, ?.,n in a distribution, then the mean is

    A)                 1             

    B)                 n

    C)                 \[\frac{1}{n}\]        

    D)                 \[\frac{2}{n+1}\]

    Correct Answer: D

    Solution :

               Mean \[=\frac{1.1+\frac{1}{2}.2+\frac{1}{3}.3+\frac{1}{4}.4+\frac{1}{5}.5+.....+\frac{1}{n}.n}{1+2+3+.....+n}\]                                           \[=\frac{1+1+1+1+.....+1}{\frac{n(n+1)}{2}}\]\[=\frac{n}{\frac{n(n+1)}{2}}=\frac{2}{n+1}\].


You need to login to perform this action.
You will be redirected in 3 sec spinner