1.  If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55 and 60, then the average marks of all the students is :
A. 53.33
B. 54.68
C. 55
D. None of these

Answer: Option B

Explanation:

Required average :

= 55 x 50 + 60 x 55 + 45 x 60
55 + 60 + 45
= 2750 + 3300 + 2700
160
= 8750
160
= 54.68