Find sum of first 15 terms of the following series
20,3,22,9,24,27,26,81.....

• the total sum is equal to the sum of AP and GP.
  Sum of AP gives : n/2(2a+(n-1)d)= 216
  since a=20,d=2 and n=8;
  for gp sum is a(r^n-1)/r-1=3279
  since a=3 and n=7
  hence total is 3279+216=3495
• 8 years agoHelpfull: Yes(41) No(9)
• The total sum is equal to the sum of AP and GP.
  Sum of AP gives : n/2(2a+(n-1)d)= 216
  since a=20,d=2 and n=8;
  for gp sum is a(r^n-1)/r-1=3279
  since a=3 and n=7,r=3;
  hence total is 3279+216=3495
• 8 years agoHelpfull: Yes(12) No(3)
• the series is 20 22 24 26 28 30 32 and 3 9 27 81 243 729
  so first 5 numbers are 20 3 22 9 24 27 26 81 28 243 30 729 32 2187 34
  sum of these numbers is 3495
• 9 years agoHelpfull: Yes(9) No(5)
• Answer is 3495.
  Every odd placed number of the sequence is + 2 of the previous odd placed number and the even placed number is previous even placed number * 3
  so 20 which is 1st number, the 22 is 3rd number and there difference is 2 similarly difference between 3rd and 5th place number is also 2 so odd placed number total comes to 20 + 2 = 24 + 2 = 26 + 2 = 28 + 2 = 30 + 2 = 32 + 2 = 34 hence 20+22+24+26+28+30+32 = 216. in the case of even placed number 3 * 3 = 9 * 3 = 27 * 3 = 81 * 3 = 243 * 3 = 729 *3 = 2187 hence 3 + 9 + 27 + 81 + 243 + 729 + 2187 = 3279
  
  total = total of odd placed numbers + total of even place numbers = 216 + 3279
  total = 3495
• 8 years agoHelpfull: Yes(9) No(3)
• i dont think what i am going to say is correct or not correct just check this,
  20,3,22,9,24,27,26,81,....
  the 15 terms are,
  20,3,22,9,24,27,26,81,28,243,30,729,32,2187,34
  10*2,3^1,11*2,3^2,12*3,3^3,...goes on till 15 terms
  ans is 3495. is it correct guys?
  
• 8 years agoHelpfull: Yes(9) No(5)
• ans. is 28
  20,22,24,26...all are difference b/w 2 and next term will 28
• 8 years agoHelpfull: Yes(8) No(23)
• there are total 8 terms of arithmetic progression with sum=216 and 7 terms of geometric progression with sum 3279 so total sum equals to 3279+216=3495
• 8 years agoHelpfull: Yes(4) No(1)
• 28, ( 20+0,3^1,20+2,3^2,20+4,3^3,20+6,3^4,20+8)
• 8 years agoHelpfull: Yes(2) No(5)
• 1309 It contains 8 numbers from arthmetic progression with a=20, d=2,l=34 sum of which is 216 and GP with a=3, r=3, sum 1093 so Total =1309
• 8 years agoHelpfull: Yes(1) No(3)
• Alternative numbers added 2 i.e., 20, 22, 24, 26
  and next alternative numbers is 3^1,3^2,3^3.
  Answer is 28
  
• 8 years agoHelpfull: Yes(1) No(4)
• 28
  two series are thsi 20,22,24,26,28
  3,3*3,9*3,27*3,
• 8 years agoHelpfull: Yes(1) No(2)
• please send capgemini model questions in cocubes to jananijeya6@gmail.com
• 8 years agoHelpfull: Yes(1) No(0)
• 34
  by differnence at odd value is 2 by counting 8 th value
• 8 years agoHelpfull: Yes(0) No(8)
• 20
  20+2=22
  22+2=24
  24+2=26
  26+2=28
  
  
• 8 years agoHelpfull: Yes(0) No(5)
• 3495 It is a combination of A.p Series And G.p Series
• 8 years agoHelpfull: Yes(0) No(1)
• odd terms of dat series are add by 2 den we get next odd term of dat series,even terms of d series is multiplied by 3 den we get another even term of dat series i.e., 20+2=22,22+2=24...., d 3*3=9,9*3=27,27*3=81...,
  ans 3495
• 8 years agoHelpfull: Yes(0) No(0)
• 7
  the answer is 7.because 15th no term is the increse by two and at each step and its is 34.
  so 3+4=7
  
• 8 years agoHelpfull: Yes(0) No(3)
• 20+3+22+9+24+27+26+81+28+163+30+489+32+1497+34=2455
  even serial numbers adding 2,like
  20+2=22,
  22+2=24
  odd serial number is multiple of 3,like
  3*3=9
  9*3=27
  
• 8 years agoHelpfull: Yes(0) No(1)
• 20+2=22
  22+2=24
  24+2=26
  26+2=28
• 8 years agoHelpfull: Yes(0) No(1)
• In the above series....the even terms difference is 2 i.e.,22-20=2
  the even terms there are 3,3^2,3^3......
  hence the now the value is 28.
• 8 years agoHelpfull: Yes(0) No(0)
• Series is
  20,3,22,9.......2187,32
  So the sum is =(20+22+24+....+32)+(3+9+27+...+2187)
  =3495
• 8 years agoHelpfull: Yes(0) No(0)
• alternate series answer 28
• 8 years agoHelpfull: Yes(0) No(1)
• alternate terms 20,20+2,22+2,24+2,"26+2 equals 28"...
  other series is 3, 3^2,3^3,..
  hence answer is '28'
  
• 8 years agoHelpfull: Yes(0) No(0)
• 28 since the first number and the alternate numbers are getting added up by 2
• 8 years agoHelpfull: Yes(0) No(0)
• answer 28 because
  +2,3^n
• 8 years agoHelpfull: Yes(0) No(0)
• Answer-28
  20,22,24,26...all are difference b/w 2 and next term will 28
• 8 years agoHelpfull: Yes(0) No(0)
• 1.20,22,24,26..... 2.3,9,27,81,.... so answer is 28
• 8 years agoHelpfull: Yes(0) No(0)
• odd places-20,22,24,26,28
  even places-3,9,27,81,....
  so answer is 28
• 8 years agoHelpfull: Yes(0) No(0)
• The first alternate numbers (i.e., 20,22,24,26,..)are added by 2 to each number (20+2=22) (22+2=24) and so on.
  The second alternate numbers (i.e., 3,9,27,81) which the results are multiples of 3 (1*3=3) now the result is 3 so take that result and again multiply by 3 (3*3=9) (9*3=27) similarly do till we get the total no of 15 terms
  Therefor,
  20 + 3 + 22 + 9 + 24 + 27 + 26 + 81 + 28 + 243 + 30 + 729 + 32 + 2187 + 34=3495
  
  
• 8 years agoHelpfull: Yes(0) No(2)
• separate odd terms and even terms
  => 20+22+24+26+28+30+32+34 (=numbers at 1st, 3rd, 5th ... 8th position)
  => 3+9+27+81+(81*3)+(81*9)=(81*27) (=geometric progression 3, 3^2, 3^3 .... and these are even position terms)
  => for the first series sum1 = 8/2(20+34)=236
  =>for the second series sum2 =3(3^7 -1)/(3-1)= 3279
  so sum1+sum2=236+3279=3515
• 7 years agoHelpfull: Yes(0) No(1)
• it is a combination of one AP and one GP. 8 Terms of AP with first term 20 and common difference 2 and 7 terms of GP with first term 3 and common ratio 3. Sum of 8 terms of AP are 216 and 7 terms of GP are 3279. Total asked sum is 3495
• 7 years agoHelpfull: Yes(0) No(0)
• It's ans is 28 because in this question has 2 series .first is addition of 2 like 20,22,24,26.
  and second is multiple of 3 like 3,9,27,81....
• 7 years agoHelpfull: Yes(0) No(0)
• 3495
  1st number plus 2 and 2 nd number is powers of 3
• 7 years agoHelpfull: Yes(0) No(0)
• 3,9,27,............. 7 terms in G.P.
  HENCE S7=3*(3^7-1)(3-1)=3279
  20,22,24,..........................8 terms in A.p
  s8=8/2[2*20 + 7*2]=216
  hence total sum=3495
• 7 years agoHelpfull: Yes(0) No(0)
• ans is 3495
  because series contains numbers like 20,22,24,26,28,30,32,34
  and multiple of 3 i.e. 3,9,27,81,243,729,2187
  so sum of these all integers will be 3495.
• 7 years agoHelpfull: Yes(0) No(0)
• Ans is 3495
  it is series of arithmetic and geometric progress alternatively.
  20,22,24 is arithmetic series and it comes n=8 times in this series so sum of all those elements can be found out by
  s=n/2(2(a1) + (n-1)d)=216
  geometric series comes n=7 times
  s= a((1-r^n)/1-r)=3279
  an addition of both will give me ans=3279+216=3495
• 7 years agoHelpfull: Yes(0) No(0)
• 20+22+24+26+......+upto 8th term = 8/2(20*2+(8-1)*2)=(40+14)*4=54*4=216
  3+9+27+......+upto 7th term=3(3^7-1)/(3-1)=3279
  sum of first 15 terms = 216 + 3279 = 3495
• 7 years agoHelpfull: Yes(0) No(0)
• the number series difference is + 2 and multiply by 3 i.e 20+2 alternate and 3*3=9 so
  so the series will be as v have to calculate 15 terms so series
  20,3,22,9,24,27,26,81,28,243,30,729,32,2187,34
  so add this series u will get answer as 3495
• 7 years agoHelpfull: Yes(0) No(0)
• The complete series is 20,3,22,9,24,27,26,81,28,243,30,729,32,2187,34
  Total sum is 20+3+22+9+24+27+26+81+28+243+30+729+32+2187+34=3495
• 7 years agoHelpfull: Yes(0) No(0)
• (20+22+24.....+34) + (3 + 3^2 + 3^3.....+3^7) = 216 + 3279 = 3495
• 7 years agoHelpfull: Yes(0) No(0)
• 28
  20+2=22
  22+2=24
  24+2=26
  26+2=28
• 7 years agoHelpfull: Yes(0) No(0)
• sum of AP=n/2(2a+(n-1)d)
  a=20,d=2,n=8
  sum of AP=216
  sum of GP=a((r^n)-1)/r-1
  a=3,r=3,n=7
  sum of GP=3279
  then sum of first 15 terms=sum of AP + sum of GP
  =216+3279
  =3495
• 4 years agoHelpfull: Yes(0) No(0)