Mike took 5 mock tests before appearing for the GMAT. In each mock test he scored 9 points more than the previous mock test. If he scored 760 on the GMAT and his average score for the mocks and the GMAT was 726.67, what was the difference in the score of his last mock and his GMAT score? Choose the correct choice from the following answers
A) 22	B) 30	C) 40	D) 50	E) 60
One way to do this would be weighted average method..   1) let the average of 5 mocks be x...   so take it as a mix of5 quantitites of xand1 quantity of 760resulting in an average of 726.67...   By alligation/weighted average..   the difference in 760 and 726.67 is 5/6 of difference of 760 and x..   760-726.67 = 5/6 * (760-x)   760-x= 33.33*6/5=40...   so x = 720..   the last of mock test will be 720+9+9=738...   so ans = 760-738= 
<gadget id="calculator">760-738</gadget>
<output>22</output>
22   22
<result>A</result>
Mike took 5 mock tests before appearing for the GMAT. In each mock test he scored 9 points more than the previous mock test. If he scored 760 on the GMAT and his average score for the mocks and the GMAT was 726.67, what was the difference in the score of his last mock and his GMAT score?