arithmetic

posted by .

What is the sum to 15 terms of an arithmetic progression whose 8th term is 4?

  • arithmetic -

    W.k.t,
    Sn = n/2 {2a + (n-1)d} then
    S15 = 15/2 {2a + 14d}
    =15/2 {2(a+7d)}
    wkt, a+7d = 15
    S15 = 15(15)=225

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Maths

    1) In the arithmetic progression, the 8th term is twice the 4th term and the 20th term is 40. Find the common difference and the sum of the terms from the 8th to the 20th term inclusive. 2) Find the least number of terms of the AP, …
  2. arithmetic

    an arithmetic progression has 20 terms. the sum of all the even terms is 350. given that the first term is 5, find the common difference and the eleventh term.
  3. arithmetic

    In an arithmetic progression the sum of the first 10 terms is 50 and the 5th is three times the second term. Find the fisrt term and the common difference.
  4. maths

    1) The first term of arithmetic progression is -20 and the sum of it's term is 250. find it's last term if the number of it's terms is 10 2) Find the fifth term from the arithmetic progression -12, -9, -6 hence find the sum of it's …
  5. Math

    A sequence is called an arithmetic progression of the rst order if the di erences of the successive terms are constant. It is called an arith- metic progression of the second order if the di erences of the successive terms form an …
  6. Maths

    1..The first 2 terms of a geometric progression are the same as the first two terms of an arithmetic progression.The first term is 12 and is greater than the second term.The sum of the first 3 terms od the arithmetic progression is …
  7. math

    The first, the third and the seventh terms of an increasing arithmetic progression are three consecutive terms of a geometric progression. In the first term of the arithmetic progression is 10 find the common difference of the arithmetic …
  8. A.P AND G.P AND A.M AND G.M

    Find the arithmetic progression and sum of its first 20 terms whose arithmetic mean and geometric mean between first and third term is 10 and 8 respectively
  9. math

    The 3rd term of an Arithmetic Progression is 10 more than the first term while the fifth term is 15 more than the second term. Find the sum of the 8th and 15th terms of the Arithmetic Progression if the 7th term is seven times the …
  10. math

    An arithmetic progression as the same first and second terms as the geometric progression. Find the sum of the first 20 terms of the arithmetic progression. How do I do this?

More Similar Questions