if the average of terms of the given series 148,146,144,142,140.....is 125,then find the total number of tems in series

• 24 terms
  
  Average of terms = (a+l)/2
  125= (148+l)/2
  l=102
  also
  l= a+(n-1)*d
  here a=148,l=102,d=-2
  hence
  solving we get
  n= 24
• 12 years agoHelpfull: Yes(29) No(2)
• Let, there be n terms.
  sum of n terms=n/2(2a+(n-1)d). where, a= 1st term d=common difference
  here,a=148 d=-2
  
  now, sum of n terms=n/2(2*148+(n-1)*-2)
  Average ={n/2(2*148+(n-1)*-2)}/n
  According to question :
  average=125
  so, {n/2(2*148+(n-1)*-2)}/n =125
  =>n=24.
• 12 years agoHelpfull: Yes(13) No(1)
• 125= (148+146+144+142)/4
  ==> 145-125=20
  we consider 4 terms so +4 = 20 +4 =24
• 12 years agoHelpfull: Yes(4) No(1)