IBPS Clerk Prelims Model Paper 21

A needs 80 (10 × 8) hours to complete the work alone.
Similarly, B and C need 120 (15 × 8) hours and 60 (20 × 8) hours, respectively.
A and B work for 36 (6 × 6) hours together.
So, work done by them = 36 (

1

80

+

1

120

)+

H

160

= 1,
where H is the number of hours C has to work to complete the remaining work.
∴ H = 40 hours
So, C needs 4 days if he works 10 hours a day.