The sum of 11 terms of an AP whose middle term s 30 is

(1) 320 (2)330 (3)340 (4)350

n=11 (this is the total no of terms)

(a1 + a11)/2 = 30 (sum of first and eventh term)

which gives a1 + a11 = 60 (first and 11th term)

now sum of AP = n x (a1 + a11) /2

= 11 x 60 /2

= 11 x 30

= 330

Hope this helps. Thumbs up if you comprehendo ! xD