Question

Find the sum of all odd integers between 2 & 100 divisible by 3.

Answer 1

Find the sum of all odd integers between 2 & 100 divisible by 3.

Good question,

Here is your perfect answer!

Odd integers btw 2&100 are 3,9,15,21...99.

Here d= 6.

To find n,

=) an = a + (n-1)6

=) 99 = 3 + (n-1)6

=) 99-3 = (n-1)6

=) 96/6 = n-1

=) 16 = n-1

=) 17 = n

Since Sn = n/2 (a + l)

S17 = 17/2 * (3+99)

= 17/2 * 102

= 17* 51

= 867.

Answer 2

odd number = 3,9,15,21.........99

a=3

d=9-3=6

99= a + (n-1)d

99= 3 + (n-1)6

99= 3 + 6n -6

99+3=6n

102=6n

n=17

sum of the number

S17 = 17/2 (a+ last term)

S17= 17/2(3+99)

S17=17/2(102)

S17=17×51

S17=867