The average age of three boys is 15 years. If their ages are in the ratio 3:5:7 the average age of the young boy is ______ years?

-18
-9
-9
-18

• avg of three boys is 15 years given ratio of their ages are 3:5:7
  let x be the age
  (3x+5x+7x)/3 =15 implies x=3
  then the age of the young boy is 3x3=9
  ans option
• 10 years agoHelpfull: Yes(14) No(0)
• 3X+5x+7x=45
  x=3
  age of youngest =3x=9
• 10 years agoHelpfull: Yes(5) No(0)
• answer=9
  since average=15 and number of observation=3
  so total=15*3=45
  age of young boy is=45*3/15=9
  
• 10 years agoHelpfull: Yes(1) No(0)
• total ratio 3:5:7=15
  avg=15
  sum%3=15
  sum=15*3=45
  young=3
  (3%15)*45=9
  sol is 9
• 9 years agoHelpfull: Yes(1) No(0)
• 9, as x=3 then 3*3=9
• 9 years agoHelpfull: Yes(1) No(0)
• 9
  3x+5x+7x=45
  x=3
  youngest age is =9
• 9 years agoHelpfull: Yes(1) No(0)
• The options updated are
  -18
  -9
  -7
  -18
• 10 years agoHelpfull: Yes(0) No(0)
• @Arpit: Can you explain the formula used in it pls :)
• 10 years agoHelpfull: Yes(0) No(0)
• ANS WILL BE 9.... TOTAL SUM OF THE AGE OF THREE BOYS IS (3*15)=45.. SO (3a+5a+7a)=45... a=3... young boy is (3*3)=9 years old.
• 9 years agoHelpfull: Yes(0) No(0)
• 3x+5x+7x/3=15
  x=3
  9
• 9 years agoHelpfull: Yes(0) No(0)
• none of these, as from avg. 3x+5x+7x=15x/3=15
  x=3, so the younger most have the age is 21
• 9 years agoHelpfull: Yes(0) No(4)
• (3x+5x+7x)/3=15
  15x=45
  x=3
  age of younger boy = 3*3 = 9
• 9 years agoHelpfull: Yes(0) No(0)
• total age is 3*15=45yrs
  divide 45 by (3+5+7)x=3
  so each 3*3=9
• 9 years agoHelpfull: Yes(0) No(0)
• 45*3/15=9
  
• 9 years agoHelpfull: Yes(0) No(0)
• let,the ratio be 3x:5x:7x
  therefore
  3x+5x+7x/3=15
  15x=45
  x=3
  the age of the young boy is=3x3=9years
• 9 years agoHelpfull: Yes(0) No(0)
• 3x+5x+7x=15*3
  x=3
  age of the youngest= 3*3=9years
• 9 years agoHelpfull: Yes(0) No(0)
• the avg is = 3*15 = 45yrs
  the ratio is 3:5:7= 3*3:3*5:3*7 = 9:15:21
  the ans is 9
  
  
• 9 years agoHelpfull: Yes(0) No(0)
• 9
  age of young boy=(3/15)*45
• 9 years agoHelpfull: Yes(0) No(0)
• the avg is = 3*15 = 45yrs
  the ratio is 3:5:7= 3*3:3*5:3*7 = 9:15:21
  the ans is 9
• 9 years agoHelpfull: Yes(0) No(0)
• let age of 3 boys b x, y ,z.
  so,total age=x+y+z=3*15.
  =45.
  ratio of dere ages=3:5:7=15
  youngest age,x=(45/15)*3
  =9years.
  
• 9 years agoHelpfull: Yes(0) No(0)
• first assume the one boy is x, 2nd is y ,and 3rd is z
  ratio of ages of three boys are 3:5:7
  now solve this we get 3x+4y+7z/3=15
  on solving we get 15/3=15
  5x=15= x=15/5=3
  now the age of young boy is 3x put value of x in this now we get 3*3=9
  age of young boy is=9
• 9 years agoHelpfull: Yes(0) No(0)
• 3x+5x+7x=45
  x=3
  youngest age is =9
• 9 years agoHelpfull: Yes(0) No(0)
• 3x+5x+7x)/3 =15 implies x=3
  then the age of the young boy is 3x3=9
• 9 years agoHelpfull: Yes(0) No(0)
• 9 yrs
  taking the ratio (3x+5x+7x)/3 = 15
  15*3=15x
  hence x=3
  thus youngest has the age of (3x=3*3=9yrs)
• 9 years agoHelpfull: Yes(0) No(0)
• sum of the age of three boys=3x15=45yrs
  age of the young boy=3x45/15=9yrs
• 8 years agoHelpfull: Yes(0) No(0)
• 3x+5x+7x=45;
  x=3
  so young boy is (3*3) 9 years
  
• 8 years agoHelpfull: Yes(0) No(0)
• (3x+5x+7x)/3=15
  15x=45
  x=3
  i.e.. young boy =3x
  =3(3)=9
• 8 years agoHelpfull: Yes(0) No(0)
• (15*3)/(3+5+7)=3
  3*3=9
• 8 years agoHelpfull: Yes(0) No(0)
• average age of 3 boys=15*3=45
  3k+5k+7k=45
  15k=45
  k=3
  3*3=9 is the answer
• 8 years agoHelpfull: Yes(0) No(0)