Question

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

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

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Answer 1

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

Answer 2

Answer:

Right answer is (2) 330.

Step-by-step explanation:

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

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

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

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

=> 11*60/2

=> 11*30

=> 330

Hope it helps.....