The average student age of a certain class which has 30 students is 10. If one student aged 11 go to another class and the age of the class teacher is included the average changes to 11. What is the age of class teacher?
Pick:
A) 32
B) 41
C) 45
D) 48
E) 50
Sum of ages of class before replacement= 30x10=300   Sum of ages of class without teacher= 300-11= 
<gadget id="calculator">300-11</gadget>
<output>289</output>
289   Sum of ages of class after replacement=30x11=330   Age of teacher=330-289= 
<gadget id="calculator">330-289</gadget>
<output>41</output>
41   Answer: 41
<result>B</result>
The average student age of a certain class which has 30 students is 10. If one student aged 11 go to another class and the age of the class teacher is included the average changes to 11. What is the age of class teacher?