A group of 630 children is arranged in rows for a group photograph session. Each row contains three fewer children than the row in front of it. What number of rows is not possible

• Let the no. of students in front row be x.
  So, the no. of students in next rows be x–3,x−6,x–9 ... so on
  
  If n i.e. no. of rows be then no. of students (n=3)
  x+(x–3)+(x–6)=630
  3x=639
  x = 213
  So possible,
  Similarly for n = 4
  x+(x–3)+(x–6)+(x−9)=630
  4x–18=630
  x=162
  
  If n = 5
  (4x–18)+(x−12)=630
  5x–30=630
  x=120
  Again possible.
  
  If n = 6
  (5x−30)+(x−15)=630
  6x−45=630
  6x=675
  
  x is not Integer
  Hence n can not be 6
• 9 years agoHelpfull: Yes(4) No(0)