IBPS SO Prelims Exam Model Paper 2

Given:
A can do a piece of work in 30 days
B can do the same work in 18 days.
B starts the work and continues for 6 days alone then A joins him.
Assumption:
Take LCM of the time taken by A and B.
Lcm = 90 units (total work)
Formula used:
Efficiency = Total work/Time
Calculation:
Efficiency of A =

90

30

= 3 units per day (∵ efficiency =

total‌work

time

)
Efficiency of B =

90

18

= 5 units per day (∵ efficiency =

total‌work

time

)
B works alone for 6 days and completes = 6 × 5 = 30 units.
Remaining work = 90 - 30 = 60 units.
According to the question,
Remaining work is done by both (A + B) in time =

60

(3+5)

= 7(

1

2

) days