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Averages
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
Read Solution (Total 29)
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- 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 - 10 years agoHelpfull: Yes(1) No(0)
- 9, as x=3 then 3*3=9
- 10 years agoHelpfull: Yes(1) No(0)
- 9
3x+5x+7x=45
x=3
youngest age is =9 - 10 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.
- 10 years agoHelpfull: Yes(0) No(0)
- 3x+5x+7x/3=15
x=3
9 - 10 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 - 10 years agoHelpfull: Yes(0) No(4)
- (3x+5x+7x)/3=15
15x=45
x=3
age of younger boy = 3*3 = 9 - 10 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 - 10 years agoHelpfull: Yes(0) No(0)
- 45*3/15=9
- 10 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 - 10 years agoHelpfull: Yes(0) No(0)
- 3x+5x+7x=15*3
x=3
age of the youngest= 3*3=9years - 10 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
- 10 years agoHelpfull: Yes(0) No(0)
- 9
age of young boy=(3/15)*45 - 10 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 - 10 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.
- 10 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 - 10 years agoHelpfull: Yes(0) No(0)
- 3x+5x+7x=45
x=3
youngest age is =9 - 10 years agoHelpfull: Yes(0) No(0)
- 3x+5x+7x)/3 =15 implies x=3
then the age of the young boy is 3x3=9 - 10 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) - 10 years agoHelpfull: Yes(0) No(0)
- sum of the age of three boys=3x15=45yrs
age of the young boy=3x45/15=9yrs - 9 years agoHelpfull: Yes(0) No(0)
- 3x+5x+7x=45;
x=3
so young boy is (3*3) 9 years
- 9 years agoHelpfull: Yes(0) No(0)
- (3x+5x+7x)/3=15
15x=45
x=3
i.e.. young boy =3x
=3(3)=9 - 9 years agoHelpfull: Yes(0) No(0)
- (15*3)/(3+5+7)=3
3*3=9 - 9 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 - 9 years agoHelpfull: Yes(0) No(0)
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