#06 Darts challenge
Everyone knows that on a regular dartboard you can score 180 with three darts, by getting three treble twenties. However, there are scores below 180 that you can鈥檛 get with three darts.
What is the lowest score you can鈥檛 get with three darts? And for that matter, what is the lowest score that you can鈥檛 get with two darts? And with one dart? (You can of course score zero with a dart, simply by missing the board.)
Answer next week
#05 Murphy鈥檚 law of socks Solution
The first sock that I lose is guaranteed to create an odd sock. There are now five socks left, an odd sock plus two pairs.
The chance that the next lost sock will create a new odd sock is therefore 4/5, or 80 per cent.
Now we have four socks left, two odd socks and one pair, so the chance that the third lost sock will break up the final pair is 2/4, which is also 1/2 or 50 per cent.
The chance of having three odd socks after three washes is therefore 4/5 x 1/2 = 2/5 (or 40 per cent). That means there is only a 60 per cent chance that I won鈥檛 end up with three odd socks after three washes, i.e. that I still have one pair intact.
This helps to explain the commonly shared experience that washing machines seem to generate odd socks.
Quick quiz #06
1 What celestial object did US astronomer Clyde Tombaugh discover in 1930?
2 Low-density lipoprotein, or LDL, is more commonly known as what when found to excess in the bloodstream?
3 In Einstein鈥檚 special relativity, what mathematical transformation determines how times dilate and lengths contract when objects are moving?
4 The smallest pair of amicable numbers is 220 and 284. What makes them amicable?
5 The beaches around Tortuguero on Costa Rica鈥檚 Caribbean coast are known for their large numbers of which nesting animal?
Answers below
Quick quiz #06
Answers
1 Pluto
2 鈥淏ad鈥� cholesterol (high-density HDL is 鈥済ood鈥�)
3 Lorentz transformation
4 The sum of the divisors of the first number (excluding itself) adds up to the second
5 Sea turtles
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