Ok, I did a practise Powerprep question and this was part of the last question I got on the test. It was a question where you had to choose which of the following MUST be true, so here is what the ETS people said
If the average (arithmetic mean) of x, y, z, 5 and 7 is 8, then
III. The range of the five numbers is 2 or more.
According to ETS, III is true. However, how can the range of these five numbers be 2? If the average is 8, this means that x+y+z=28. So in the case where we have the least "spread out" numbers, we'll have for x, y and z 9,9,10, and the range for all five numbers then will be 10-5=5.
So I don't understand how you can get a range of 2, in my opinion III is not true.
Any takes?
Thanks