What is the average (arithmetic mean) of the numbers 5, 6, 7, 7, 8, and 9? Choose the most appropriate option.
A) 4.2 B) 6.5 C) 6 D) 7 E) 8
{5, 6, 7, 7, 8, 9}={7-2,7-1, 7, 7,7+1,7+2} --&gt; the average = 7.   Answer: 7.
<result>D</result>
What is the average (arithmetic mean) of the numbers 5, 6, 7, 7, 8, and 9?