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If x is the average (arithmetic mean) of m and 9, y is the average of 2m and 15, and z is the average of 3m and 18, what is the average of x, y, and z in terms of m?

A) m+6
B) m+7
C) 2m+14
D) 3m+21​


Sagot :

Answer:

ANSWER EXPLANATION: Since the average (arithmetic mean) of two numbers is equal to the sum of the two numbers divided by 2, the equations x=

m+9

2

, y=

2m+15

2

, z=

3m+18

2

are true. The average of x, y, and z is given by

x+y+z

3

. Substituting the expressions in m for each variable (x, y, z) gives

[

m+9

2

+

2m+15

2

+

3m+18

2

]

3

This fraction can be simplified to m+7.

The final answer is B.