Average age of total 80 students from three classes, V, VI and VII, is 13 years. Average age of 30 students of class V is 11 1/2 years. If average age of another 30 students of class VI is 12 1/2 years, what is the average aage of rest of 20 students of class VIII ?  Select the correct option: A) 13 1/2 years B) 14 1/2 years C) 15 years D) 16 years E) 5 years
Explanation :   Sum of ages of 80 students = 80 x 13 = 1040   Sum of ages of 30 students of class V = 30 x 11.5 = 345   Sum of ages of 30 students of class VI = 30 x 12.5 = 375   ∴ Total age of 20 students of class VII = 1040 - 345 - 375= 
<gadget id="calculator">1040 - 345 - 375</gadget>
<output>320</output>
320   ∴ Average age= 320/20= 
<gadget id="calculator">320/20</gadget>
<output>16</output>
16 years.   Answer : Option 16 years
<result>D</result>
Average age of total 80 students from three classes, V, VI and VII, is 13 years. Average age of 30 students of class V is 11 1/2 years. If average age of another 30 students of class VI is 12 1/2 years, what is the average aage of rest of 20 students of class VIII ?