Two pipes A and B can fill a tank in 10 and 20 minutes respectively.If both pipes are opened simultaneously,after how many minutes should pipe B be closed so that the tank is full in 8 minutes?
A. 3 min
B. 4 min
C. 2 min
D.5 min
Out of 8 crew members 3 particular members can sit only on the left side.Another 2 particular members can sit on the right side.Find the number of ways in which the crew can be arranged so that four men can sit on each side
Pure mathematics is the world's best game. It is more absorbing than chess, more of a gamble than poker, and lasts longer than Monopoly. It's free. It can be played anywhere - Archimedes did it in a bathtub.
Richard J. Trudeau, Dots and Lines
Sometimes it is useful to know how large your zero is.