If m is the average (arithmetic mean) of the first 10 positive multiples of 3 and if M is the median of the first 10 positive multiples of 3, what is the value of M – m ?  Choose the correct choice
A) –5 B) 5 C) 0 D) 25 E) 27.5
The first 10 positive multiples of 3 is an evenly spaced set. One of the most important properties of evenly spaced set (aka arithmetic progression) is:in any evenly spaced set the arithmetic mean (average) is equal to the median.   Hence M=m --&gt; M-m=0.   Answer: 0.
<result>C</result>
If m is the average (arithmetic mean) of the first 10 positive multiples of 3 and if M is the median of the first 10 positive multiples of 3, what is the value of M – m ?