Birthday Paradox (Birthday Problem)
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 […]
Logic Puzzle: Inverting the glasses
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 […]
Upstream-Downstream relative speed question
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?
Fastest horse Interview question
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?
Number of Rectangles on a chess board
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?
value of expression
What is the value of 1/2 of 2/3 of 3/4 of 4/5 of 5/6 of 6/7 of 7/8 of 8/9 of 9/10 …. of 99/100 of 1000?
Time and Speed puzzle
Two friends decided to get together and start riding bikes towards each other, both at a speed of 6 km/hr (starting at the same time). The live 36 km apart and hence will meet halfway. One of them have a pet pigeon and it starts flying the instant the friends start traveling. The pigeon flies […]
Effect on area of rt angled triangle if base is increased and hight reduced
If the base of a Right angled triangle is increased 4 times and height is reduced to half, what will be the effect on its area ?
