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11th Class Mathematics Sequence and Series Question Bank Sequence and Series (A.P., G.P. and H.P.)

  • question_answer
    Insert two harmonic means between \[\frac{1}{20}\] and \[\frac{1}{32}\]

    A)  \[\frac{1}{24},\frac{1}{26}\]                

    B)  \[\frac{1}{24},\frac{1}{28}\]

    C)  \[\frac{1}{26},\frac{1}{30}\]                

    D)  \[\frac{1}{30},\frac{1}{31}\]

    Correct Answer: B

    Solution :

    (b): After inserting the harmonic means Let the harmonic progression be \[\frac{1}{a},\frac{1}{a+d},\frac{1}{a+2d},\frac{1}{a+3d}\] \[\Rightarrow \]\[a=20;a+3d=32\] \[\Rightarrow \]\[d=4\] \[\therefore \] The required harmonic means are \[\frac{1}{24},\frac{1}{28}\]


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