An Eternal Quest for Incremental Improvement

The gentlemen Dutch, English, Painter, and Writer are all teachers at the same secondary school. Each teacher teaches two different subjects.

Furthermore:

- Three teachers teach Dutch language
- There is only one math teacher
- There are two teachers for chemistry
- Two teachers, Simon and mister English, teach history
- Peter doesn't ...

What is the smallest number of red balls that must be moved to transform the red triangle into the green triangle?

There are ten coin machines. Each machine produces coins that weigh 10 g, expect one faulty machine which produces coins that weigh 9 g. You are given with an electronic weighing scale. You can take any number of coins from any machine and use the weighing scale. What would be ...

You have sixteen coins. One of them is a counterfeit, and the other fifteen are genuine, but identical in appearance to the counterfeit. The counterfeit's weight is different from that of a genuine coin, but you don't know if the counterfeit is heavier or lighter than a genuine ...

The planet Pfooey is inhabited by robots. Half of the robots always tell the truth, but the other half have been affected by a bug in their software that causes them to lie at all times. All of the robots look exactly alike, so it can be confusing to figure ...

There are three bags. First bag has 2 black balls, second one has 2 white balls and the third has a black ball and white ball. The labels for the bags are prepared as 2B, 2W and BW respectively. While fixing the labels, they were intentionally wrongly placed in all ...

If you had only one match and entered a *cold* and *dark* room, where
there were a fire place, an oil lamp and a candle, which would you light
first?

You are driving by car to a particular destination, and our only assumption is that you are free to drive at any speed you choose - no traffic jams or anything like that. For the first half of the journey (and by half we mean half the overall distance between the ...

One day Kerry celebrated her birthday. Two days later her older twin brother, Terry, celebrated his birthday. How come?

Itâ€™s cold outside! Betty and her husband were speculating last night that this has been the coldest winter they can remember. Out of curiosity, they decided to check out the old newspaper records for this week in their area during past years and were astonished at what they found ...