Here, first term = a = 17

Common difference = 9

Last term = l = 350

To find: number of terms and their sum.

Let there be n terms in the AP.

Since, l= 350

∴ 350 = 17 + (n - 1)9

⇒ 350 - 17 = 9n - 9

⇒ 333 = 9n - 9

⇒ 333 + 9 = 9n

⇒ 9n = 342

⇒ n = 38

Therefore number of terms = 38

Now, Sum of n terms of this arithmetic series is given by:

S_n = [2a + (n - 1)d]

= [a + a + (n - 1)d]

= [a + l]

Therefore sum of 38 terms of this arithmetic series is given by:

∴ S₃₈ = [17 + 350]

= 19 × 367

= 6973

∴ n= 38 and S_n = 6973