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: Choose the correct choice from the following choices.
A) 53.33 B) 54.68 C) 55 D) 56 E) None of these
Explanation:   Required average = (55 × 50 + 60 × 55 + 45 × 60/55 + 60 + 45)   = (2750 + 3300 + 2700/160)   = 8750/160   = 54.68   Answer: 54.68
<result>B</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: