The average of seven numbers is 9. The average of first three numbers is 7 and the average of last three numbers is 11. What is the middle number? Options
A) 7	B) 8	C) 9	D) 11	E) 10
The total of seven numbers = 7X9 = 63   The total of first 3 and last 3 numbers is = 3 X 7+3 X 11 = 54   So, the middle number is  (63 - 54 )= 
<gadget id="calculator"> (63 - 54 )</gadget>
<output>9</output>
9   9
<result>C</result>
The average of seven numbers is 9. The average of first three numbers is 7 and the average of last three numbers is 11. What is the middle number?