Question

find the sum of all natural number between 200 and 400 which are divisible by 7​

Answer 1

Answer:

The numbers lying between 200 and 400, which are divisible by 7, are

203, 210, 217, ­­­­­­­­… 399

∴First term, a = 203

Last term, l = 399

Common difference, d = 7

Let the number of terms of the A.P. be n.

∴ an = 399 = a + (n –1) d

⇒ 399 = 203 + (n –1) 7

⇒ 7 (n –1) = 196

⇒ n –1 = 28

⇒ n = 29

s29=29/2 (203+399)

      = 29/2(602)

      = (29)(301)

      =8729      

Thus, the required sum is 8729.

Explanation:

Answer 2

heya,. here is your answer

if it helped you mark it as brainliest answer and follow