• Q. First term is of arithmatic progression sequence is 31 and the difference between consecutive numbers is 5 , Find the sum numbers 20th, 21th, 22th, 23th and 24th terms.
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  • Sum of 20 position is (20/2)[2*31 + (20 - 1)x 5 ]

    = (10)[62 + (19)x 5 ]

    = (10)[62 + 95 ]

    = (10)[157]

    ie. S20 = (1570)

  • Sum of 21 position is (21/2)[2*31 + (21 - 1)x 5 ]

    = (10.5)[62 + (20)x 5 ]

    = (10.5)[62 + 100 ]

    = (10.5)[162]

    ie. S21 = (1701)

  • Sum of 22 position is (22/2)[2*31 + (22 - 1)x 5 ]

    = (11)[62 + (21)x 5 ]

    = (11)[62 + 105 ]

    = (11)[167]

    ie. S22 = (1837)

  • Sum of 23 position is (23/2)[2*31 + (23 - 1)x 5 ]

    = (11.5)[62 + (22)x 5 ]

    = (11.5)[62 + 110 ]

    = (11.5)[172]

    ie. S23 = (1978)

  • Sum of 24 position is (24/2)[2*31 + (24 - 1)x 5 ]

    = (12)[62 + (23)x 5 ]

    = (12)[62 + 115 ]

    = (12)[177]

    ie. S24 = (2124)

  • so the sequance of the sum numbers from position are.
    S20 = 1570
    S21 = 1701
    S22 = 1837
    S23 = 1978
    S24 = 2124

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