Question

P can do a job in 15 days. In how many days can P and Q together complete the job if Q is twice as fast as P?​

Answer 1

Answer:

5 days

Step-by-step explanation:

P's work is a day = 1/15

Q's work is a day = 2/15

One day work of both together =1/15+2/15=3/15

Total days=15/3=5 days

Answer 2

Answer:

In 5 days, P and Q together complete the job if Q is twice as fast as p

Step-by-step explanation:

Given that,

P can do a job in 15 days

Q is twice as fast as p

Therefore,

Q can do a job in= 15/2= 7.5

How many days can P and Q together complete the job

 Together complete job = ab/(a+b)

Where,

A is the days taken by P

B is the days taken by Q

Thus,

Together complete job = (15*7.5)/(15+7.5)

                                       = 112.5/22.5

                                       =  5

Thus in 5 days, P and Q together complete the job if Q is twice as fast as p