If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is:
Choices:
A) 50
B) 51.47
C) 51.49
D) 53
E) 54.68
Required average   = (55 x 50 + 60 x 55 + 45 x 60)/(55 + 60 + 45)   = (2750 + 3300 + 2700)/160   = 8750/160   = 54.68   Answer is 54.68
<result>E</result>
If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is: