The amazing race

One of the Israeli TV channels broadcasts a reality show called 'the race to the million', a licensed version of the American TV show, 'The amazing race'. The prize from the American show is $1 million dollars, whereas the winners of the Israeli show win only NIS 1 million (about four times less) and in reality, only NIS 750,000 after tax is paid. Such is life. This is the only reality show that I can watch parts of without breaking out with a rash. This is not the sort of TV programme that I would normally write about, but the current episodes display a puzzle that I thought I would share here.

There are three jerrycans: one holding 10 litres, one holding 7 litres and one holding 3 litres. The 10 litre jerrycan is full of petrol. The puzzle is to obtain one jerrycan holding 5 litres petrol (without spilling any, of course).

In order to show the steps, I'll use the following table, where the three columns at the end show the contents of the three jerrycans after the action has been taken. Instead of writing 'the 10 litre jerrycan' or similar every time, I'll label the jerrycans A, B and C.

Action	10 l (A)	7 l (B)	3 l (C)
Initialisation	10	0	0
Move 3 from A to C	7	0	3
Move 3 from C to B	7	3	0
Move 3 from A to C	4	3	3
Move 3 from C to B	4	6	0
Move 3 from A to C	1	6	3
Move 1 from C to B*	1	7	2
Move 7 from B to A	8	0	2
Move 2 from C to B	8	2	0
Move 3 from A to C	5	2	3

* This is the critical step in my opinion. Every other move uses the full capacity of whichever jerrycan is being used (normally C); this is this only step with a different amount.

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As can be seen, this blog uses a 'spoiler' button. I had great difficulty with getting this to work; as far as I can understand, the button works when viewed after 'publication', which is what all visitors to the blog can see. But the button doesn't work when I am writing the blog nor when I am previewing it. I'm leaving this note to myself for the next time that I use a 'spoiler' button.

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This day in history:

Blog #	Date	Title	Tags
47	13/08/2006	Graduation show	Fairport Convention, Canterbury sound, Bar mitzva, Music festivals
1065	13/08/2017	Road 38 is brought into the 21th century!	Personal
1251	13/08/2019	Night walking (2)	Walking
1414	13/08/2021	Back to the graveyard	Kibbutz, Father