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)
Posted on: 24 January 2018 by Don Atkinson
0.333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333333
Etc
Nice one IB !
there is another possibility of course........
Posted on: 24 January 2018 by MDS
Posted on: 24 January 2018 by Innocent Bystander
I’ll throw another one in, in case anyone feels like a change. Punctuate the following so that it makes complete sense:-
time flies you cannot they fly at such irregular intervals
Posted on: 24 January 2018 by Don Atkinson
Time flies ? You can’t ! They fly at such irregular intervals !
Posted on: 24 January 2018 by Don Atkinson
Looks good to me 
Posted on: 24 January 2018 by Innocent Bystander
Time flies ? You can’t ! They fly at such irregular intervals !
Well done! Maybe not as much of a challenge as I thought it might be - adults often get hung up on tempus fugit rather than insects. It is actually a question from an 11-plus exam in the 1950s
Posted on: 24 January 2018 by Don Atkinson
Time flies ? You can’t ! They fly at such irregular intervals !
Well done! Maybe not as much of a challenge as I thought it might be - adults often get hung up on tempus fugit rather than insects. It is actually a question from an 11-plus exam in the 1950s
Ah ! Now, I did my 11-plus exams, there were two stages, in the late 1950s. But I don’t recall that particular question 
Posted on: 24 January 2018 by Innocent Bystander
Mine wasn’t until mid 60s. I seem to recall (rather vaguely) there was an “intelligence test” with various puzzles, and maths and English. That one was from someone I knew in the late 1970s, some years older than me, who remembered it from his own 11-plus, but I don’t know exactly whixh year.
Posted on: 25 January 2018 by Don Atkinson
Another "language" one, especially since IB seems to prefer these to "maths" ones
Posted on: 25 January 2018 by Don Atkinson
And another "maths" one for everybody else................
Posted on: 25 January 2018 by Innocent Bystander
64 just for you, Don. I dont usually bother with the simple maths ones, whilst I tend to tacke the geometric ones when I have time as I find them morecinteresting!
Posted on: 25 January 2018 by Innocent Bystander
Another "language" one, especially since IB seems to prefer these to "maths" ones
The best I can do is T (NOT FUSED), but somehow I don’t think that was what was intended, HVe to look again when my brain is fresh.
Now if the S was an O...
Posted on: 25 January 2018 by dave marshall
Confused?
Surely not that straightforward? 
Posted on: 25 January 2018 by NFG
There are two goats in a field: goat 1 has a leash of 30 metres, goat 2 has a leash of 40 metres.
They share 10% of each others grass, how far apart are the posts securing the leash?
Posted on: 25 January 2018 by Don Atkinson
Confused?
Surely not that straightforward?
"Well, after that struggle with Farmer Watts and his 100 acre field system, I thought something a tad more "gentle" on these old brains might be in order......." (that was my introduction to these last few teasers)
Not everything has to be confusing dave ! Somethings in life can be straightforward. And this, in itself, sometimes surprises us.
But as you can see, what one person considers straightforward, others don't.
Well done !
Posted on: 25 January 2018 by Don Atkinson
Another "language" one, especially since IB seems to prefer these to "maths" ones
The best I can do is T (NOT FUSED), but somehow I don’t think that was what was intended, HVe to look again when my brain is fresh.
Now if the S was an O...
I guess by now you have seen dave's contribution ?
But there might well be other solutions.
Posted on: 26 January 2018 by Don Atkinson
Hi NFG,
I am struggling slightly to grasp your teaser. This could just be me having a mental block !
I visualize two goats, each tethered such that Goat No.1 can eat a circle of grass radius 30m ie 2829 sqm. A second Goat can eat a circle of grass radius 40m ie 5029 sqm. These two circles overlap. The overlap being an area of grass common to both Goats. This area could vary from zero ( where the posts are 70m or more apart) up to 2829 sqm (where the posts are no more than 10m apart).
However, this area of grass, common to both goats, is specific in terms of square metres. For example, if it is 283 sqm (ie 10% of the smaller circle, then it is only 5.6% of the larger circle.
Can you appreciate my mental block, given the 10% wording of your teaser ?
Or, more likely, am I just being dumb !
Posted on: 26 January 2018 by Innocent Bystander
The only explanation I could envisage is the larger circle being close enough to a boundary wall to restrict its area. But if that is the case, you could equally well have them both partially cut off by walls, with any number of answers.
Posted on: 26 January 2018 by Don Atkinson
The only explanation I could envisage is the larger circle being close enough to a boundary wall to restrict its area. But if that is the case, you could equally well have them both partially cut off by walls, with any number of answers.
Looks like you are having similar "mental blocks" ?
Posted on: 26 January 2018 by Innocent Bystander
At present, seems so. Looking for the catch/twist: grass not all over, some other limitation ... all variable.
Posted on: 27 January 2018 by Don Atkinson
This diagram illustrates my initial interpretation of NFG's puzzle.
Clearly the overlap which both goats can eat, can't be, (at the same time), 10% of each goat's chomping ground.
So, although I consider the diagram represents NFG's words, I doubt if it represents the intended puzzle......
......unless you know differently
Posted on: 27 January 2018 by Innocent Bystander
Precisely, Don. As I suggested, a possible bit of missing information might be a boundary to the field cutting off part of at least the larger circle -maybe that stake against a wall.
Posted on: 27 January 2018 by Don Atkinson
Or.........
.......perhaps he had in mind the scenario illustrated above, whereby:-
the "Red" goat eats the common grass to the right hand side of the "vertical" dividing line, and
the "Yellow" goat eats the common grass to the left hand side of the "vertical" dividing line.
But I don't consider the above diagram represents the text of NFG's puzzle.
Posted on: 27 January 2018 by Don Atkinson
Precisely, Don. As I suggested, a possible bit of missing information might be a boundary to the field cutting off part of at least the larger circle -maybe that stake against a wall.
Yes......good idea...........
Putting the stake against a N-S wall (ie cutting the red circle in half), would reduce the red grass to 2515 sqm.
However, putting the wall "slightly" to the left of the stake, would reduce the red field to 2829 sqm ie precisely HALF the area of the yellow grass. The yellow post then needs to move L-R until the overlap area = 283 sqm.
BUT
This is not what NFG's puzzle says !
Posted on: 27 January 2018 by Don Atkinson
Now, i'm pretty sure this one is straightforward ! (I hope !)
Ignore the colours, they are only there to make it look pretty !
The red, green and yellow triangles show some sort of consistent relationship between the three external numbers and the fourth, internal number.
What is the "missing" internal number in the blue triangle ?
