The average marks of a class of 30 students is 40 and that of another class of 50 students is 80. Find the average marks of all the students? Choose the most appropriate option:
A) 52.5  B) 52.9  C) 52.1  D) 52.3  E) 65
Sum of the marks for the class of 30 students = 30 * 40= 
<gadget id="calculator">30 * 40</gadget>
<output>1_200</output>
1200   Sum of the marks for the class of 50 students= 50 * 80= 
<gadget id="calculator">50 * 80</gadget>
<output>4_000</output>
4000   Sum of the marks for the class of 80 students=   1200 + 4000= 
<gadget id="calculator">1200 + 4000</gadget>
<output>5_200</output>
5200   Average marks of all the students= 5200/80= 
<gadget id="calculator">5200/80</gadget>
<output>65</output>
65   Answer:65
<result>E</result>
The average marks of a class of 30 students is 40 and that of another class of 50 students is 80. Find the average marks of all the students?