Not Just About Numbers John D Barrow How
Not Just About Numbers John D Barrow
How to Rig an Election 24 people vote for 8 candidates (A, B, C, D, E, F, G, and H). The ‘voters’ divide up into 3 groups with preferences 1 st group: A B C D E F G H 2 nd group: B C D E F G H A 3 rd group: C D E F G H A B Looks like C is the preferred choice
But H’s Mum wants him to win! 1 st group: A B C D E F G H 2 nd group: B C D E F G H A 3 rd group: C D E F G H A B F bts G 3 -0, E bts F 3 -0, D bts E 3 -0, C bts D 3 -0, B bts C 2 -1 A bts B 2 -1 and finally H bts A 2 -1 So H wins the tournament!
The Three-Box Trick Monty Hall – 2 goats and 1 car
Start by choosing Box 1 1 Prob = 1/3 2 3 Prob = 1/3 Prob = 2/3 2 Prob = 2/3 now open 3 Prob = 0 So you should switch to Box 2
You are Twice As Likely to Win if You Switch than if You Stay !
An Unnecessarily High Five
Juan Melé Marco Recortado No. 3 (1946)
Monkey Puzzle
8 years of parallel computing
A completely predictable world
Pretty Mean Prices Retail price indices AM = (p 1 + p 2 +…+ pn)/n. GM = (p 1 p 2 … pn)1/n Politicians like the geometric mean because AM GM note that 0 (x – y)2 = x 2 + y 2 -2 xy so ½(x+y) (xy) Price Index = AM(2008)/AM(2007) Doesn’t work if units of the prices are mixed And they are!
August 2008 August 2007 Milk £ 0. 42 per pint £ 0. 35 per pint Beef mince £ 4. 40 per kg £ 3. 70 per kg Unleaded petrol £ 1. 2 per litre £ 1. 03 per litre = ? ? all cancel! always works
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