Q. The ages of Old and Young total 48. Old is twice as old as Young was when Old was half as old as Young will be when Young is three times as old as Old was when Old was three times as old as Young. How old is Old?
Q. Two towns are linked by a railroad. Every hour on the hour a train leaves each town for the other town. The trains all go at the same speed and every trip from one town to the other takes 5 hours. How many trains are met by one train during one trip?
Q. A man has two bags with 10 mangoes each. On his way home he needs to cross five gates which are guarded by watchmen. Every gate the man crosses, that gate's watchmen will take out two mangoes from each bag with mangoes. Can the man take home any mangoes after crossing all five gates. If yes how many and how?
Q. A group of workers was put on a job. From the second day onwards, one worker was withdrawn each day. The job was finished when the last worker was withdrawn. Had no worker been withdrawn at any stage, the group would have finished the job in two-thirds of the time. How many workers were there in the group?
Q. My room has a square window of 4 feet across and 4 feet down. I decided to get only half the area of the window painted. Even after the painting, I found that the clear part of the window still remained a square and still measured 4 feet from top to bottom and 4 feet from side to side. How is it possible?
Q. Four whole numbers - a, b, c and d.
such that -
1. ( a + b + c + d ) is a perfect square
2. ( a + b ), ( a + c ), ( a + d ), ( b + c ) , ( b + d ) and ( c + d ) are also each a perfect square. What are the smallest values for a, b, c and d?
Q. There is a grid of 20 squares by 10 squares each having unit edge length. How many rectangles are there having area 'x' sq units,where x is an odd integer?
Note that square is a rectangle.
Solution
total number of rectangles including squares of odd area
= (20+18+16+14+12+10+8+6+4+2)(10+8+6+4+2) = 110*30 = 3300
You're an electrician working at a mountain. There are N wires running from one side of the mountain to the other. The problem is that the wires are not labeled, so you just see N wire ends on each side of the mountain. Your job is to match these ends (say, by labeling the two ends of each
wire in the same way).
In order to figure out the matching, you can twist together wire ends, thus electrically connecting the wires. You can twist as many wire ends as you want, into as many clusters as you want, at the side of the mountain where you happen to be at the time. You can also untwist the wire ends at the side of the mountain where you're at. You are equipped with an Ohm meter, which lets you test the connectivity of any pair of wires. (Actually, it's an abstract Ohm meter, in that it only tells you whether or not two things are connected, not the exact resistance.)
You are not charged [no pun intended] for twisting, untwisting, and using the Ohm meter. You are only charged for each helicopter ride you make from one side of the mountain to the other. What is the best way to match the wires? (Oh, N>2, for there is no solution when N=2.)
A mathematician is a blind man in a dark room looking for a black cat which isn't there
Charles R. Darwin
There r few things whch we knw whch r nt capable of mathmatical reasoning nd when these can nt it is a sign dt our knowledge of them is very smal nd confusd nd where a mathmaticl reasing can be had . It is as dark a foly to make use a candle stick as to g