Question

The sum of the third and the ninth term of an AP is 10. Find a possible sum of the first 11 terms of this AP. 

(a) 55 

(b) 44 

(c) 66 

(d) 48

Answer 1

Correct option (a) 55

Explanation: 

The third and ninth terms of an 11 term AP are a pair of corresponding terms of the AP. Hence, their average would be the average of the AP. This gives us the required sum of the AP as 11 × 5 = 55.