The average age 12 monkeys in a tree is 16 years. Out of these, the average age of 6 monkeys is 18 years and that of the other 6 monkeys is 13 years. The age of the 12th monkey is?  Pick:
A) 10
B) 9
C) 4
D) 6
E) 7
Age of the 12th monkey= 12*16 - (6*18+6*13) = 192-186= 
<gadget id="calculator">192-186</gadget>
<output>6</output>
6 years   Answer is 6
<result>D</result>
The average age 12 monkeys in a tree is 16 years. Out of these, the average age of 6 monkeys is 18 years and that of the other 6 monkeys is 13 years. The age of the 12th monkey is?