The average age of a group of 10 students is 14 years. If 5 more students join the group, the average age rises by 1 year. The average age of the new students is:
A. 15 years
B. 17 years
C. 16 years
D. 18 years
E. None of these

• let average age of 10 student=x/10=14, x=140.if 5 more join then average age of 15 student=y/15=15,y=225. to calculate average age of new student=(y-x)/2=
  (225-140)/2=17years
• 12 years agoHelpfull: Yes(1) No(3)
• Total age of 11 students = 14 * 10 = 140 and the total age of 15 students = 15*15= 225
  
  Let the average age of 5 new students be x.
  
  Therefore total age of the new students = 5x.
  
  Hence the total age of 15 students = 140 + 5x = 225 => x = 17.
• 5 years agoHelpfull: Yes(0) No(0)
• LET AVERAGE OF 10 STUDENTS IS T/10=14 =>T=140
  if 5 more join (i.e LET IT BE 'Y')the average rises by a year i.e (T+Y)/15=15
  from this Y=225-140
  Y=85
  Now, the average age of Y is (Y/5)=>85/5=17years
• 4 years agoHelpfull: Yes(0) No(0)