The average age of 18 persons in a office is 15 years. Out of these, the average age of 5 of them is 14 years and that of the other 9 persons is 16 years. The age of the 15th person is? Pick
A) 9  B) 31  C) 56  D) 72  E) 90
Age of the 15th student = 18*15 - (14*5+16*9) = 270-214= 
<gadget id="calculator">270-214</gadget>
<output>56</output>
56 years   Answer is 56
<result>C</result>
The average age of 18 persons in a office is 15 years. Out of these, the average age of 5 of them is 14 years and that of the other 9 persons is 16 years. The age of the 15th person is?