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If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm
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16 Aug 2018, 09:36
16 Aug 2018, 09:36
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If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithmetic mean) of a and b ?
A) 0.1
B)0.5
C)1
D)2.5
E)5
A) 0.1
B)0.5
C)1
D)2.5
E)5
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm
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17 Aug 2018, 06:54
17 Aug 2018, 06:54
3
amorphous wrote:
If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithmetic mean) of a and b ?
A) 0.1
B)0.5
C)1
D)2.5
E)5
A) 0.1
B)0.5
C)1
D)2.5
E)5
We COULD solve this system of equations for a and b, but this could take some time.
Also recognize that, to find the average of a and b, we need only find the SUM, a + b
GIVEN:
12a + 3b = 1
–2a + 7b = 9
ADD the two equations to get: 10a + 10b = 10
Divide both sides by 10 to get: a + b = 1
What is the average (arithmetic mean) of a and b?
Average = (a + b)/2 = 1/2 = 0.5
Answer: B
Cheers,
Brent
Intern
Joined: 13 Jul 2018
Posts: 33
Given Kudos: 0
GRE 1: Q159 V151
GPA: 4
WE:Programming (Computer Software)
Re: If 12a + 3b = 1 and 7b – 2a = 9, what is the average (arithm
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17 Aug 2018, 16:05
17 Aug 2018, 16:05
Taking the sum works the fastest here, as against substituting values.
