Question
Pipe P can fill a tank in 5 hours, but pipe Q can empty
it completely in 20 hours. If both are opened together, find the time needed to fill the tank.Solution
Let tank capacity = 20 litres {LCM (5 and 20)} Efficiency of filling pipe P = (20/5) = 4 units/hour Efficiency of emptying pipe Q = (20/20) = 1 unit/hour Net working efficiency = 4 – 1 = 3 units/hour Required time = (20/3) = 6.66 hours
Select the correct mirror image of the given combination when the mirror is placed at ‘ MN ’ as shown.
Identify the mirror image of the following figure when the mirror XY is placed to the right of the figure.
Select the correct mirror image of the given combination when the mirror is placed at ‘XX’ as shown.
Select the correct mirror image of the given figure when the mirror is placed to the right side of the f igure at ‘PQ’ .
Select the correct mirror image of the given figure when the mirror is placed as shown below.
Select the correct mirror image of the given combination when the mirror is placed at 'AB' as show.

In the following question, choose the correct mirror-image from among the four alternatives (1), (2), (3) and (4) given along with it. The mirror may ...
Identify the mirror image of the following figure when the mirror is placed to the right of the figure.
I f a mirror is placed on the line MN, then which of the answer figures is the correct image of the question figure?