Man - Hour - Work

Q1. A man has to travel from a point P to a point Q, 256 km apart. He travels half the
distance on day one, half of the remaining distance on day two, half of the
remaining distance on day three and so on. He reaches exactly at the point Q
(A) in 8 days
(B) in 16 days
(C) in 24 days
(D) never

Q2. A pipe can fill an empty tank in 6 hours, while another pipe can empty the full tank
in 8 hours. If both the pipes are opened together when the tank is half full, then the
tank will be full in
(A) 6 hours
(B) 12 hours
(C) 18 hours
(D) 20 hours
 

1>d.He never reaches his

1>d.
He never reaches his destination

2>B 12 hrs.

2>B 12 hrs.

A pipe can fill an empty :

Q2. A pipe can fill an empty tank in 6 hours, while another pipe can empty the full tank
in 8 hours. If both the pipes are opened together when the tank is half full, then the
tank will be full in
(A) 6 hours
(B) 12 hours
(C) 18 hours
(D) 20 hours
 
Sol:
To completely fill the tank pipe A takes 6 hours so the amount of tank filled in 1 min= 1/8.
To completely empty the tank B takes 8 hours so the amount emptied in 1 min = 1/6.

Let the time taken to full the tank when it is half full, by opening the two pipes be "x" hours.

So, x(1/6-1/8)=1/2
Solving, X= 12 hours.

 

__________________

n/a

or by another way:

2nd problem can be also solved by this way,
x(1/3-1/4)=1

Solving,
X=12 hours.

So,ans:(b) 12 hours.

__________________

n/a

or by another way:

Q2. A pipe can fill an empty tank in 6 hours, while another pipe can empty the full tank
in 8 hours. If both the pipes are opened together when the tank is half full, then the
tank will be full in
(A) 6 hours
(B) 12 hours
(C) 18 hours
(D) 20 hours
 
Sol:
x(1/3-1/4)=1

Solving,x=12 hours.
So,ans:(b) 12 hours

__________________

n/a

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