Question

. P and Q together can do a work in 12
days. Q and R in 6 days. P and R in 4
days. If P, Q, R work together they will
complete the work in :
(a) 2 days
(b) 4 days
(c) 5 days
(d) s days​

Answer 1

Step-by-step explanation:

total = 12

P+Q Efficiency =1

Q+R Efficiency =2

R+P Efficiency =3

2 {P+Q+R} = 6

P+Q +R=3

TIME = 12/3 = 4 DAYS

Answer 2

Step-by-step explanation:

p and q one day work is 1/p + 1/q = 1/12

q and r one day work is 1/q + 1/r = 1/6

p and r one day work is 1/p + 1/r = 1/4

substituting 2nd equation in 1st we get

(1/p)+(1/6-1/r) = 1/12

1/r - 1/p = 1/12 and 1/r + 1/p = 1/4 solving these two equations we get r= 6 days p= 12 days and substituting r value in 2nd equation we get

q= 0

when p q r work together they complete in 4 days so option b