Re: In 2007, the arithmetic mean of the annual incomes of Jack a
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01 Jul 2020, 23:18
Assuming that the annual incomes are equal to:
Jess=x
Jack=y
Jill=z
The problem is asking for the arithmetic mean of the three, this is equal to (x+y+z)/3
We know that:
The arithmetic mean of Jack and Jill incomes can be expressed as=
(y+z)/2 =3800...............(1)
The arithmetic mean of Jill and Jess incomes can be expressed as=
(z+x)/2 =4800...............(2)
The arithmetic mean of Jess and Jack incomes can be expressed as=
(x+y)/2 =5800...............(3)
The result of the sum of the left terms of (1),(2) and (3) is equal to = 2(x+y+z)/2
Reducing we obtain
x+y+z
So the sum of the right terms should be divided by 3 to get the answer
Result= 14400/3 = 4800
Answer=D