Students of three different classes appeared in common examination. Pass average of 10 students of first class was 45%, 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?  Options.
A) 74%  B) 75%  C) 67%  D) 72%  E) None
Solution:   Sum of pass students of first, second and third class,   = (45% of 10) + (60% of 15)+ (80% of 25)   = 4.5+9+20= 
<gadget id="calculator">4.5+9+20</gadget>
<output>33.5</output>
33.5   Total students appeared,= 10+15+25= 
<gadget id="calculator">10+15+25</gadget>
<output>50</output>
50   Pass average,= 33.5*100/50= 
<gadget id="calculator">33.5*100/50</gadget>
<output>67</output>
67%.   Answer: Option 67%
<result>C</result>
Students of three different classes appeared in common examination. Pass average of 10 students of first class was 45%, 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?