The sum of the fourth and twelfth term of an arithmetic progression is 20. What is the sum of the first 17 terms of the arithmetic progression?  Pick one:
A) 300  B) 120  C) 150  D) 170  E) 270
n th term of A.P. is given by a+(n-1)d   4 th term = a+3d   12 th term = a+11d   Given a+3d+a+11d=20 --&gt; 2a+14d=20 --&gt; a+7d = 10   Sum of n term of A.P = n/2[2a+(n-1)d]   subsitiuing n = 17 ...we get 17/2[ 2a + 14d] = 17 [a+7d] = 17*10 = 170...   Answer is 170...
<result>D</result>
The sum of the fourth and twelfth term of an arithmetic progression is 20. What is the sum of the first 17 terms of the arithmetic progression?