Question

find the sum of all odd number bewteen 351 and 373

Answer 1

Smallest odd number between 351 and 373 = 353

Greatest odd number between 351 and 373 = 371

First term = a1 = 353

Common difference = 2 (odd numbers only)

Find the number of terms:

an = a1 + (n - 1)d

371 = 353 + (n - 1)2

371 = 353 + 2n - 2

371 = 351 + 2n

2n = 371 - 351

2n = 20

n = 10

Find the sum:

Sn = n/2 (a1 + an)

Sn = 10/2 (353 + 371)

Sn = 3620

Answer: The sum of all odd numbers between 351 and 373 is 3620

Answer 2

In the attachment I have answered this problem.

The solution is simple and easy to understand.

See the attachment for detailed solution.