The sequence 1,2,3,-4,5,6. Find the average and sum of first 200 numbers.

• 1 + 2 + 3 + (-4) + 5 + 6 + 7 + (-8) + 9 + 10 + 11 + (-12) + 13 + ........... + 198 + 199 + (-200)
  
  = 1 +2 + 3 +5 + 6 + 7 + 9 + 10 + ........... + 198 + 199 - ( 4+ 8 + 12 + ........ + 200)
  
  = 1 + 2 + 3 + 5 + 6 + 7 + ... + 199 - ( 4+ 8 + ... + 200) + ( 4 + 8 + 12 + .... + 200 ) - ( 4 + 8 + 12 + .... + 200)
  
  ( adding and subtracting the series of 4 to 200 )
  
  = 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + .... + 199 + 200 - 2 ( 4 + 8 + 12 + .... + 200)
  
  = 1 + 2 + 3 + ..... + 200 - 8 ( 1 + 2 + ..... + 50)
  
  = [200*201]/ 2 - 8*[ 50*51]/2
  
  = 20100 - 10200
  
  = 9900
  
  Sum of the series = 9900
  
  Average = 9900/200 = 49.5
• 11 years agoHelpfull: Yes(36) No(4)
• sequence= 1,2,3,-4,5,6.
  so we can form 198 term(row),
  199th is again 1, 200th term is 2..
  so 1,2 can be 34 times in 200..
  3,-4,5,6 can be 33 times in the 200..
  sum=(1*34)+(2*34)+(3*33)+(-4*33)+(5*33)+(6*33)=432..
  hence there are 200 numbers..
  avg=432/200 =2.16...
  the answer will be 2.16
• 11 years agoHelpfull: Yes(28) No(7)
• in the sequence 1->>34 times
  2->>34times
  3->>33times
  -4-->>33times
  5-->> 33 times
  6-->>33times
  
  so average will be (33(1+2+3-4+5+6) +1+2) / 200
  answer is : 2.16 ans
  
• 11 years agoHelpfull: Yes(5) No(8)
• plz explain..can't understand...how 34 or 33 times
• 11 years agoHelpfull: Yes(3) No(0)
• z 49.5 z d ans?
  
• 11 years agoHelpfull: Yes(1) No(2)
• sum=39600 avg=198
• 11 years agoHelpfull: Yes(1) No(2)