Explanation Average marks of batch1 = 50
Students in batch1 = 55
Total marks of batch1 = 55 × 50
Average marks of batch2 = 55
Students in batch2 = 60
Total marks of batch2 = 60 × 55
Average marks of batch3 = 60
Students in batch3 = 45
Total marks of batch3 = 45 × 60
Total students = 55 + 60 + 45 = 160
Average marks of all the students
= [(55×50)+(60×55)+(45×60)]160
= [ 275+330+270 ]/16 .
= 875/16 .
= 54.68.