the sum of 3rd and 9th term of A.P is 8. find the sum of 1st 11 terms of A.P Pick one:
A) 33	B) 22	C) 44	D) 55	E) 66
A.P. series is a, a+d, a+2d, a+3d, a+4d,..............nth terms   where a = first term   d = common difference   We have to given,   sum of 3rd and 9th terms = 8   (a+2d)+(a+8d) = 8   2a+10d = 8   a+5d = 4.............(1)   formula, Sum of 1st 11 terms of AP   S = n[ 2a+(n-1)d ]/2   =11[ 2a+(11-1)d ]/2   =11[a+5d]   =11[4] ( from eq. ...(1) )   S = 44   ANSWER:44
<result>C</result>
the sum of 3rd and 9th term of A.P is 8. find the sum of 1st 11 terms of A.P