Intern
Joined: 21 Jan 2021
Posts: 7
Location: Argentina
Concentration: General Management, Technology
Re: The average age of three groups of people is: Group x = 83 years, Grou
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26 Jan 2021, 13:05
I´ve found another way. Maybe more complicated but still another option.
You know that the average of X and Y is 79, so you need to calculate:
(83x+76y)/(x+y)=79
It gives you the x:y ratio: 4:3
On the other hand, you have the average of Y and Z, meaning you calculate the same as previous:
(76y+85z)/(y+z)=81
It gives you the y:z ratio, which is 5:4
Combining both, you will realize that the ratio x:y:z is 12:15:20
In detail: 12= 4*3 (x*y), 15= 3*5 (y1*y2) and, finally, 20= 5*4 (y2*z).
The statement is asking you to find the average of x, y and, z. Now you have everything you need to do it:
(83*12+76*15+85*20)/(12+15+20)
Being x=12, y=15 and z=20, as I said before.
This results in 81,5 approx., which is answer B.