Students of three different classes appeared in common examination. Pass average of 10 students of first class was 70%, pass average of 15 students of second class was 60% and pass average of 25 students of third class was 80% then what will be the pass average of all students of three classes? Select the correct option
A) 74% B) 75% C) 69% D) 72% E) None
Solution:   Sum of pass students of first, second and third class,   = (70% of 10) + (60% of 15)+ (80% of 25)   = 7+9+20= 
<gadget id="calculator">7+9+20</gadget>
<output>36</output>
36   Total students appeared,= 10+15+25= 
<gadget id="calculator">10+15+25</gadget>
<output>50</output>
50   Pass average,= 36*100/50= 
<gadget id="calculator">36*100/50</gadget>
<output>72</output>
72%.   Answer: Option 72%
<result>D</result>
Students of three different classes appeared in common examination. Pass average of 10 students of first class was 70%, pass average of 15 students of second class was 60% and pass average of 25 students of third class was 80% then what will be the pass average of all students of three classes?