AFCAT I 2020 Solved Paper

Let the total work = LCM of 10, 15 and 20 =60 units

P+Q can do in 10 days ∴

in 1 day P+Q can complete = 60/10 of work = 6 units

similarly,

Q+R can do in 15 days so Q+R in one day is 60/15 = 4 units

R+P can do in 20 days so in one day R+P can do is 1/20 = 3 units

So one day work of P+Q+R = (6+4+3)/2 = 13/2 = 6.5

One day of P's work = (P+Q+R)-(Q+R) = 6.5 -4 = 2.5

Similarly
R’s efficiency= 6.5 - 6 = 0.5
Q’s efficiency = 6.5 - 3 = 3.5


R’s time =

60

0.5

=120 days
Q’s time =

60

3.5

=

120

7

days
P’s time =

60

2.5

=24 days