Latest GRE Aptitude Question SOLUTION: The average age of 10 students in a group increases by 0.4 years when a girl of age 6 years is replaced by another girl. The age of the new girl is 16.4 yrs 10 yrs 12 yrs 16 yrs 20

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The average age of 10 students in a group increases by 0.4 years when a girl of age 6 years is replaced by another girl. The age of the new girl is
16.4 yrs
10 yrs
12 yrs
16 yrs
20 yrs

Asked In GRE Vijesh Jain (11 years ago)

Solved Mihir Read Solution (4)

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Read Solution (4) :

Mihir  (11 years ago)

Let initial average =x

Sum of ages of 10 students of initial group =10x
Sum of ages of replaced group = 10*(x+0.4) = 10x+4

so age of new girl is 4 years more than girl of 6 yrs.
so age of new girl = 6+4=10 years.

Is this solution Helpfull? Yes (11) | No (2)  

Balakrishnan M  (11 years ago)

The average age of 10 students = (Sum of the age of 10 students)/10
A = x/10 ---(1)
when a girl of age 6 years is replaced by another girl.
Another girl age is y.
Then,
New average age is,
(A+0.4) = (x-6+y)/10
Solving,
(x/10)+0.4= (x-6+y)/10
(x+4)/10 = (x-6+y)/10
(x+4)= x-6+y
y = 10 years
The age of the new girl is 10 Years.

Is this solution Helpfull? Yes (2) | No (3)  

Vinay Sipani   (11 years ago)

11

initial => x / 10 = y
After => (x - 6 + m)/10 = y + 0.5

Solving both , m = 11 years

Is this solution Helpfull? Yes (1) | No (10)  

hemanth  (11 years ago)

10*0.4=4
4*6=24,
24-4=20years

Is this solution Helpfull? Yes | No (2)  

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