CDS 2009 (II) Mathematics Q1

05:19 , 0 Comments

Q1.  P and Q can do job in 2 days. Q and R can do it in 4 days; and P and R in 12/5 days. What is the number of days required for P alone to do the job?

Soln:

 Job done by P and Q in 1 day = 1/2

 Job done by Q and R in 1 day = 1/4

 Job done by P and R in 1 day=5/12 


Job done by P, Q and R in 1 day = [(1/2)+(1/4)+(5/12)]/2 = 7/12.

The work done by P in 1 day = (Job done by P, Q and R) - (Job done by Q and R) = 7/12 - 1/4 = 1/3.

Number of days required for P to do the job  alone = 3 days.

Itachi443

Some say he’s half man half fish, others say he’s more of a seventy/thirty split. Either way he’s a fishy bastard.

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