#110 Reflecting on time
As I was travelling by coach one night, I noticed that the conventional seven-segment illuminated clock at the front of the vehicle was reflected in the window to my side.
What caught my eye at the time, 22:01, was that the reflected image said it was 10:55, which, although incorrect, still read like a legitimate time.
Later on my travels, I took another coach trip. At one point, I nodded off. Waking with a start as the vehicle entered a tunnel, I saw the time reflected in the window and, for a moment, was convinced that what I saw was the right time.
鈥淎 longer nap than I thought,鈥� I said to myself, before realising what had happened. It was an easy mistake to make because the difference in minutes between the reflected and the actual time was the minimum that was possible. And if we hadn鈥檛 entered the tunnel, I might never have spotted it.
What time was it when I woke up?
Answer next week
#109 Chocs-a-weigh
Solution
Here is one way. Number the machines 1 to 6. If you take one chocolate bar from machine 1, two from machine 2 and so on, up to five bars from machine 5, you will have 15 bars that weigh 3 kilograms in total, minus 5 grams for each bar from the faulty machine.
If you divide the weight shortfall in grams by 5, it will tell you the number of the faulty machine. So a weight of 2.98 kg means that machine 4 is faulty (20/5). If the 15 bars weigh exactly 3 kg, then the faulty machine is number 6.
Quick quiz #98
1 What name is given to the altitude at which Earth鈥檚 atmosphere ends and space begins?
2 Which ruminant species was affected by a mass bacterial infection in 2015, resulting in the deaths of around 200,000 individuals?
3 In what year was the first commercial 8-bit processor released?
4 The Wilson cycle describes the opening and closing of what?
5 Dupuytren鈥檚 contracture affects which part of the body?
Answers on page 55
Answers
1 The K谩rm谩n line
2 The saiga antelope
3 In 1972, with the release of the Intel 8008
4 Oceanic basins
5 The hand: it is a condition in which connective tissue thickens, causing fingers to bend inwards