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lovesinging
lovesinging asks:
Q:

Anita has two sisters and three brothers.  The mean of all their ages is 6 years.  What will their mean age be 10 years from now?

In Topics: Helping my child with math
> 60 days ago

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Answers (1)

UrsulaRagazi
UrsulaRagazi writes:
This is how I answered the question. If you let the siblings be represented by the letters a,b,c,d,e,f (there are six of them including Anita), then you can set up the following equation:
(a+b+c+d+e+f)/6 = 6.
This comes from the formula for a mean.
In ten years, each sibling will have added 10 years to their age, so this is the equation for the mean of their ages ten years from now:
[(a+10)+(b+10)+(c+10)+(d+10)+(e+10)+(f+10)]/6
By adding all of the 10's in the numerator we get:
(60+a+b+c+d+e+f)/6
We can seperate this fraction into:
60/6 + (a+b+c+d+e+f)/6
60/6 = 10 and we know that (a+b+c+d+e+f)/6 = 6, so the answer is:
10+6 = 16.
So in ten years the mean age increased 10 years.
> 60 days ago

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