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
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 + bGIVEN:
12a + 3b = 1
–2a + 7b = 9ADD 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
_________________
Brent Hanneson - founder of Greenlight Test Prep