Question

find the sum of all natural number between 50 and 350 which are divisible by 5​

Answer 1

Step-by-step explanation:

this problem can be solved by Arithmetic Progression

A.P is 50, 55, 60-------350

here a = 50 , d = 5 and aₙ= 350

aₙ = a + (n-1)d

350 = 50 + (n-1)*5

350 = 50 + 5n - 5

350 = 45 + 5n

=> 5n = 350-45

=> 5n = 305

=> n = 61

now sum of 61 terms is

=> S₆₁ = 61/2 [ 2*50 + 60*5]

=> 61/2 [ 100 + 300 ]

=> 61/2 [400]

=> 200*61

=> 12200