IBPS Clerk Prelims Model Paper 20

A takes 24 days to complete a work.
B is 20% more efficient than A, hence B will take (24×100)/120 = 20 days.
C takes (20+10) = 30 days.
Time taken by A & C in completing the work
= (24×30)/(24+30)
= (24×30)/54
= 40/3 days