The first Last term of an arithmetic progression are 7 and 43 respectively. The sum of the terms of the progression is 250 Find the number of terms and common difference of the progression

Mathematics

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Given:

  • First term (a) = 7
  • Last term (L) = 43
  • Sum of the terms (Sₙ) = 250
  1. Find the number of terms (n).

    The formula for the sum of an arithmetic progression when the first and last terms are known is:
    Sₙ = (n/2)(a + L)

    Substitute the given values into the formula:
    250 = (n/2)(7 + 43)
    250 = (n/2)(50)
    Multiply both sides by 2:
    500 = n × 50
    Divide by 50 to find n:
    n = 500 / 50
    n = 10

  2. Find the common difference (d).

    The formula for the last term of an arithmetic progression is:
    L = a + (n - 1)d

    Substitute the known values (a, L, and the n we just found) into the formula:
    43 = 7 + (10 - 1)d
    43 = 7 + (9)d
    Subtract 7 from both sides:
    43 - 7 = 9d
    36 = 9d
    Divide by 9 to find d:
    d = 36 / 9
    d = 4

    The number of terms is 10 and the common difference is 4.

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