#63 What day?
“It’s Monday today, isn’t it?” pondered Angie.
“I seem to remember yesterday was Tuesday,” said Beatrice. “I believe we’re as far from Sunday as we are from Wednesday,” said Carol.
“When the day after tomorrow becomes ‘yesterday’, ‘tomorrow’ will be Tuesday,” interjected Dorothy, cryptically.
“It’s not the weekend,” said Ethel.
Clearly there was some disagreement – and if I told you how many of them had got it right, then you would be able to work out what day it is today. However, I’ve decided to keep it a secret. So who was right, and what day is it?
Answer next week
#62 Burger run
Solution
Yolanda’s estimate is closest – there are 23 shortest routes from A to B that pass through exactly one Big Burger. One way to solve this kind of puzzle is to systematically work from A and keep track of how many ways there are of reaching each point. With this problem, you should keep a separate count of how many ways there are of reaching each point after (a) zero or (b) one Big Burger visit. For line segments that contain a Big Burger, (b) becomes equal to (a), then (a) becomes equal to 0, with the “old” value for (b) effectively discarded.
Quick quiz #55
1 Which predator, renowned as the fastest in the animal kingdom, bears the name Hayabusa in Japanese?
2 The name also lends itself to the fastest production example of what type of vehicle, one that could reach a similar top speed?
3 There is a third Hayabusa, one that outpaced both of them. It arrived back from 25143 Itokawa on 13 June 2010 bearing what?
4 Istiompax indica holds the animal speed record in the sea; what is the common English name of this prized game fish?
5 The fastest human-made object reached a speed of nearly 350,000 kilometres per hour in 2018. What is it and what was it doing?
Answers on page 54
Quick quiz #55
1 The peregrine falcon, Falco peregrinus. Its swooping dives reach over 300 km/h
2 A motorcycle made by the Japanese firm Suzuki since 1999
3 An asteroid sample. The Japan Aerospace Exploration Agency probe was the first mission to land on one and take off again successfully
4 Black marlin. It has been recorded reeling out a fishing line at over 120 km/h
5 NASA’s Parker Solar Probe; it was making a close pass around the sun
Answers