A Fistful of Brain Teasers
Posted by: Don Atkinson on 13 November 2017
A Fistful of Brain Teasers
For those who are either non-British, or under the age of 65………. The UK used to have a brilliant system of currency referred to as “Pounds, Shillings and Pence”. Simplified to £ ״ s ״ d. No! Don’t ask me why the “Pence” symbol is a “d”, just learn it and remember it !
A £ comprised 20 Shillings and a Shilling comprised 12 Pence. Thus a £ comprised 240 Pence. I reckon that both Microsoft and Apple would have difficulty with these numbers in their spreadsheets, more so if we included Guineas, Crowns, Half-Crowns and Florins. However, I digress..............
The purpose of the explanation is to assist with the first two or three teasers that follow. So just to ensure a reasonable comprehension has been grasped…. ….. if each of three children has £3 − 7s − 9d, then collectively they have £10 − 3s − 3d Got the idea ? Good ! Just try 5 children, two each with £4 − 15s − 8d and three each with £3 − 3s − 4d. How much do they have between them ? (this isn’t the first brain teaser, just the basic introduction with some “homework”, the Teasers follow)
winkyincanada posted:Don Atkinson posted:The two wheels on each axle of a railway wagon are rigidly connected together.
When an engine negotiates a bend one would expect one of the wheels to skid (because one wheel has to go
further than the other).
Neither wheel skids, however, even if the rails aren't banked.
Why?PS I don't think that the solution usually quoted completely eliminates wheel skid at all speeds, but it certainly plays a significant part.
The wheels are tapered like shallow truncated cones. They move relative to the track so the outside wheel has an effectively greater diameter than the inside wheel during a turn. Super elevation of the track (banking) assists a bit, but the taper is the main thing. The taper also helps stop the wheel flanges from hitting/rubbing the rails when the train is going straight.
Nice explanation winky.
And it’s right. 
Don Atkinson posted:fatcat posted:20
It’s more than 20.
I know. A classic case of not taking enough care reading the question.
fatcat posted:Don Atkinson posted:fatcat posted:20
It’s more than 20.
I know. A classic case of not taking enough care reading the question.
I know the feeling !
Filipe posted:Don Atkinson posted:
If the double slashes mean equal length then 58
Phil
Didn’t get feedback on this, Don.
Filipe posted:Filipe posted:Don Atkinson posted:
If the double slashes mean equal length then 58
Phil
Didn’t get feedback on this, Don.
Oh dear, I know that I responded, but that response is clearly missing.
the double slashes do mean equal length and the angle is 58 deg.
Well done !
Oh! and the hypotinuse is more than 50.
I'm not sure if this process is called ITERATION or IRRITATION 
20; 13325; 5525; 1105 ;1000; 50 ..........
but you are all closing the gap !!