Question

find the sum of arithmetic series 5+11+17+......+95

Answer 1

Heya !!!

AP = 5 , 11 , 17........95




Here,


First term (A) = 5


Common Difference (D) = 11-5 = 6



Tn = 95


A + ( N -1) × D = 95


5 + ( N -1) × 6 = 95


6N - 6 + 5 = 95


6N = 95+1


N = 96/5 = 16




Therefore,



Sn = N/2 × [ 2A + ( N -1) × D ]


S16 = 16/2 × [ 2 × 5 + (16-1) × 6 ]




=> 8 × ( 10 + 90)


=> 100 × 8


=> 800


Hence,


The sum of airthmetic series 5+11+17....+95 is 800.


★ HOPE IT WILL HELP YOU ★

Answer 2

Answer:

800

Step-by-step explanation:

Last term avilable sum of arithmaetic Sn = n/2*[a+l}

a = 5, l = 95, d = 11-5 = 6, n=?

n = L-a / d + 1

  => 95 - 5 / 6 + 1

  => 90 / 6 + 1

  => 15 + 1

  => 16  

S16 = 16 / 2 * [ 5 + 95 ]

      = 8 * 100

      = 800