Answers

2016-03-21T14:01:08+08:00
  to find the common difference  d   between   34 & 42
      d   =   42- 34  =     8
      then  divide 8 by    ( 3 +1 ) =  2   /  that is,  the # of arithmetic means + 1
          thus the sum of the 3 arithmetic means =  2 + 2 + 2  =  6
0