consider the sequence 1,-2,3,-4,5,-6........what is the average of first 200 terms of sequence?

a)-1
b)0.5
c)0
d)-0.5

• 1-2+3-4+5-6....................+199-200
  = (1-2)+(3-4)+(5-6)....................+(199-200)
  = -1-1-1......................(100 terms)
  = -100
  
  so, average= (-100)/200= -0.5
  
• 9 years agoHelpfull: Yes(28) No(1)
• d)
  Taking 2 terms at time makes the series as:
  -1,-1,-1....-1 till 100 terms
  which gives the average as (-1+(-1)....-1) (till 100 terms)/200 which gives the answer as -0.5
• 9 years agoHelpfull: Yes(1) No(0)
• we have,1,-2,3,-4,5,-6....
  if we find the sum of 2 consecutive numbers then we will have,
  1+(-2)=1-2=-1
  -1+3=2
  2+(-4)=2-4=-2
  -2+5=3
  3+(-6)=3-6=-3
  -3+7=4
  4+(-8)=-4-8=-4
  .
  .
  .
  .
  so 100+(-200)=100-200=-100
  so sum of the first 200 terms= -100
  then average of the first 200 terms= -(100/200)=-0.5
  
  
• 9 years agoHelpfull: Yes(1) No(0)
• (D).. make it two sequence.. the positive n negative.. n calculate using AP.. add both the sequence sum.. n divide by 200
• 9 years agoHelpfull: Yes(0) No(0)
• 1+(-2)=-1,3+(-4)=-1,............in this way 199+(-200)=-1
  So there are 100 pairs resulting sum is =100*(-1)=-100
  so avg is=(-100)/200=-0.5
• 9 years agoHelpfull: Yes(0) No(0)
• ans is 0.5
• 9 years agoHelpfull: Yes(0) No(0)
• 1-2+3-4+5-6+.....................+199-200
  -1-1-1.......................-1 (100 terms in this series)
  
  algebric sum of 200 terms of given series= -100
  So, average of first 200 terms is = -100/200= -0.5
• 9 years agoHelpfull: Yes(0) No(0)
• -0.5
  1-2+3-4...200/200=-100/200
  =-1/2
  =-0.5
• 6 years agoHelpfull: Yes(0) No(0)