# Logic

You may solve the simple probability, “Given a set of n randomly chosen people, what is the probability of two people having same birthday?” You may also solve, “At least how many people need to be picked to make the probability 100% that at least two of them have same birthday?” Answer to the second question is […]

Four glasses are placed on the four corners of a square rotating table. Each glass is either upright (up) or upside-down (down). You have to turn all the glasses in same direction (either all up or all down). There are following conditions You are blindfolded, At one time you can only change two glasses (and […]

A person rides a cycle at a constant speed. When he drives in the direction of the wind, he is able to go 35 km in 5 hrs. While returning, when the wind was against the direction of his driving, he took 7hrs for the same distance. At what speed does he rides when there is no wind?

There are twenty five horses and you can conduct a race of only five horses at one time. There is no way to find out the absolute speed of a horse (we only know there relative speed). At least how many races will it take to determine the three fastest horses?

Earlier we discussed, how to calculate total number of squares (of all sizes) on the chess board. Here, the problem is, How many rectangles (of any size) will be there on the chess board?