The interior angle of an octagon ABCDEFGH are in AP.if the largest and second largest hav an avg of 153, find the avg of the least two?
A)117
B)131
C)141
D)cant be determined

• A) 117
  
  let the angles be
  a , (a + d) , (a +2d) , (a + 3d) , (a + 4d) , (a + 5d) , (a + 6d) and (a + 7d)
  
  Sum of all angles in octagon = 1080 = 8a + 28d
  Avg of (a + 7d) and (a + 6d) = 153 => 2a + 13d = 306
  
  solving both , a = 114 , d = 6
  
  => Avg of smallest two = (2a + d)/2 = 117
• 11 years agoHelpfull: Yes(82) No(1)
• Say a-3d, a-2d, a-d, a, a+d, a+2d, a+3d, a+4d are angles
  Sum = 8a + 4d = 1080 (eq1)
  Average of greater 2 = 2a + 7d = 306 (eq2)
  Do (eq1/2 - eq2)/2 ..which gives
  (a-5d)/2 = 117 which is the average of least 2.
  
  
• 11 years agoHelpfull: Yes(5) No(0)
• i am getting -63 as answer. what is the answer?
• 11 years agoHelpfull: Yes(0) No(12)