If the average of 20,21, 23, 24, 25, 28, 28, 29, 31 and x is 26, what is the value of x? Answers
A) 26  B) 28  C) 30  D) 31  E) 32
Sum of the deviations of the numbers in the set from the mean is always zero   20, 21, 23, 24, 25, 28, 28, 29, 31   mean is 26   so the list is -6-5-3-2-1+2+2+3+5... this shud total to zero   but this is -5 , hence we need a number that is 5 more than the mean to get a +5 and make it zero   hence the answer is  26 + 5= 
<gadget id="calculator"> 26 + 5</gadget>
<output>31</output>
31   31
<result>D</result>
If the average of 20,21, 23, 24, 25, 28, 28, 29, 31 and x is 26, what is the value of x?