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If 4 people with average age 40 years join a group, the average age of
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05 Oct 2023, 01:19
05 Oct 2023, 01:19
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If 4 people with average age 40 years join a group, the average age of the group doubles in value.
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Quantity A |
Quantity B |
Average age of the group of people initially |
20 |
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
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Free Materials for the GRE General Exam - Where to get it!!
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Free Materials for the GRE General Exam - Where to get it!!
GRE Geometry Formulas
GRE - Math Book
Re: If 4 people with average age 40 years join a group, the average age of
[#permalink]
14 Oct 2023, 06:49
14 Oct 2023, 06:49
1
let us consider that the group consists of N people, then the initial average age of the group of people is given by
<x> = S1/N where S1 is the sum of the ages of people.
Now 4 people with an average age of 40, so
40=S2/4
S2= 40*4=160
this will make the average age double, so we can write
2 <x> = (S1 + 160)/(N + 4)
2 <x> ( N + 4)= S1 + 160 As S1= N <x>
2 <x> ( N + 4)= N <x>+ 160
2 <x> ( N + 4) - N <x> = 160
<x> ( 2N -N +8) = 160
<x> (N + 8)= 160
<x>= 160/(N + 8)
let us take the least number of people in the group is 2 1.e. N = 2
<x> = 160/(2 + 8)=160/10=16
which is less than 20
Quantity A= 16
Quantity B= 20
therefore quantity B is greater than quantity A, so option B is correct.
<x> = S1/N where S1 is the sum of the ages of people.
Now 4 people with an average age of 40, so
40=S2/4
S2= 40*4=160
this will make the average age double, so we can write
2 <x> = (S1 + 160)/(N + 4)
2 <x> ( N + 4)= S1 + 160 As S1= N <x>
2 <x> ( N + 4)= N <x>+ 160
2 <x> ( N + 4) - N <x> = 160
<x> ( 2N -N +8) = 160
<x> (N + 8)= 160
<x>= 160/(N + 8)
let us take the least number of people in the group is 2 1.e. N = 2
<x> = 160/(2 + 8)=160/10=16
which is less than 20
Quantity A= 16
Quantity B= 20
therefore quantity B is greater than quantity A, so option B is correct.
gmatclubot
Re: If 4 people with average age 40 years join a group, the average age of [#permalink]
14 Oct 2023, 06:49
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