Question

P can do a piece of work in 16 days, q can do a piece of work In 12days and p,q,r can do in 4 days. Find the no of working days of r

Answer 1

Answer:

Let work done by P in 1 day = p,

Work done by Q in 1 day = q, 

Work done by R in 1 day = r

p + q = 1/12  --------eq1

q + r = 1/15   --------eq2

r + p = 1/20   --------eq3

Adding all the above, 2p + 2q + 2r = 1/12 + 1/15+ 1/20 = 12/60 = 1/5 

p+q+r=1/10--------eq4

From eq 4 & eq1 --eq4-eq1

r=1/10−1/12=6−5/60=1/60

Number of days R needs to work to complete the  work =60

Answer (A) 60