Find the sum of all numbers between 200 and 400 which are divisible by 7.
Answers
Answered by
1
The required sum is 8729
Hope this helps
Attachments:
Answered by
0
All numbers between 200 and 400
Smallest number between 200 and 400 that is divisible by 7 = 203
Largest number between 200 and 400 that is divisible by 7 = 399
a1 = 203
an = 399
d = 7
Form the AP:
an = a1 + (n - 1)d
399 = 203 + (n - 1)7
399 = 203 + 7n - 7
399 = 196 + 7n
7n = 203
n = 203 ÷ 7 = 29
Find the sum of the numbers:
Sn = n/2 (a1 + an)
Sn = 29/2 (203 + 399) = 8729
Answer: The sum is 8729
Similar questions