If 3/5 of a number is 18, that means that 1/5 is 6 as 18/3 = 6. Since 1/5 is equal to 2/10. 1/10 of the number = 3. 7/10 of the number is 3*7 which is 21.
The answer is no i hope this helps (and let me know if you need this explained)
Since the numbers are close together and you do not have any outliers, the mean would be the best measure of central tendency.
The value is
(5+6+7+8+9)/5 = 7