Puzzle 21
At midnight at the start of January 1st, Professor Stone set two old-fashioned clocks to the correct time.
One clock gains one minute every hour, and the other clock loses two minutes every hour.
When will the clocks next show the same time as each other?
When will the clocks both show the correct time?
Puzzle Copyright © Kevin Stone
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Hint
In order for the clocks to show the same time (e.g. 2 o'clock), what must the total time gained by one, and lost by the other, total?
Answers
Midnight, 10 days later, when they will both show 4 o'clock.
Midnight, 30 days later, when they will both show 12 o'clock.
Reasoning #1
In order for the clocks to show the same time, the total time gained by one, and lost by the other, must be 12 hours.
For example, if the first clock were to show 2 o'clock, it would have gained 2 hours. In order for the second clock to also show 2 o'clock, it would have had to have lost 10 hours. This is a total of 12 hours gained and lost.
We know that for every hour that passes, the first clock gains one minute, and the second clock loses 2 minutes, for a total time gained and lost of 1 + 2 = 3 minutes.
The total time gained and lost will equal 12 hours when 12 x 60 ÷ 3 = 240 hours have passed. 240 hours = 10 days.
The first clock will have gained 240 x 1 minutes = 240 minutes = 4 hours.
The second clock will have lost 240 x 2 minutes = 480 minutes = 8 hours.
So, they will both show 4 o'clock, 10 days later.
Reasoning #2
In the first answer, we can see that 10 days later, the clocks both show 4 o'clock.
If we move forward another 10 days, both clocks would show 8 o'clock.
If we move forward another 10 days, both clocks would show 12 o'clock.
This will now be the correct time.
So, they will both show 12 o'clock, 30 days later.
Puzzle 22
A 'complete' word is a word in which every letter, in turn, can be replaced by another to form a new word.
For example, RUG is a complete word because:
-ug = hug
r-g = rig
ru- = run
How many of the following words are not complete words? Proper nouns and names are not allowed.
hard
port
duck
bugs
bail
mast
thin
lean
fire
read
Puzzle Copyright © Kevin Stone
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Hint
Another example, PEN is a complete word because:
-en = ten
p-n = pin
pe- = pea
Answer
Two of the words are not complete: bugs, lean.
Reasoning
The remaining 8 words can be changed as follows:
hard:
-ard = card
h-rd = herd
ha-d = hand
har- = harp
port:
-ort = fort
p-rt = part
po-t = poet
por- = pore
duck:
-uck = muck
d-ck = deck
du-k = dusk
duc- = duct
bugs:
-ugs = hugs
b-gs = bags
bu-s = buys
bug- = ----
bail:
-ail = hail
b-il = boil
ba-l = bawl
bai- = bait
mast:
-ast = cast
m-st = most
ma-t = malt
mas- = mask
thin:
-hin = shin
t-in = twin
th-n = than
thi- = this
lean:
-ean = mean
l-an = loan
le-n = ----
lea- = leaf
fire:
-ire = hire
f-re = fare
fi-e = five
fir- = firm
read:
-ead = bead
r-ad = road
re-d = reed
rea- = real
Puzzle 23
What letter comes next in this sequence:
E O E R E {?}
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Hint
This is a very common sequence.
Answer
X.
The last letters of the words one, two, three, four, five, six.
Puzzle 24
Marathon Warm-up - Logic Puzzles
After the recent BrainBashers annual marathon, the judges were comparing notes to determine who finished where. From their notes, can you help them reconstruct the final result?
Max Merrymood beat Toby Trent and Jesse Jackson.
Pat Piper beat Jesse Jackson, Toby Trent, and Alex Ardle.
Zeb Zebra lost to Pat Piper.
Glenn Goodfellow beat Toby Trent
Zeb Zebra beat Frankie Flint.
Glenn Goodfellow lost to Frankie Flint and Pat Piper.
Toby Trent beat Billie Brick.
Alex Ardle beat Zeb Zebra, Kelly Kingfisher, and Glenn Goodfellow.
Kelly Kingfisher lost to Glenn Goodfellow and Max Merrymood.
Billie Brick beat Kelly Kingfisher.
Max Merrymood lost to Alex Ardle and Zeb Zebra.
Frankie Flint beat Toby Trent, Max Merrymood, and Billie Brick.
Toby Trent lost to Jesse Jackson and Alex Ardle.
Jesse Jackson beat Glenn Goodfellow and Billie Brick.
Puzzle Copyright © Kevin Stone
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Hint
Try rewriting the clues so that those who finished ahead are written first.
Answer
Pat Piper (P)
Alex Ardle (A)
Zeb Zebra (Z)
Frankie Flint (F)
Max Merrymood (M)
Jesse Jackson (J)
Glenn Goodfellow (G)
Toby Trent (T)
Billie Brick (B)
Kelly Kingfisher (K)
Reasoning
If we number the clues, write each name using a single letter, and rewrite the clues so that those who finished ahead are written first:
M beat T and J
P beat J, T, and A
P beat Z
G beat T
Z beat F
F and P beat G
T beat B
A beat Z, K, and G
G and M beat K
B beat K
A and Z beat M
F beat T, M, and B
J and A beat T
J beat G and B
By (2): P A
By (8): P A Z
By (5): P A Z F
By (12): P A Z F M
By (1): P A Z F M J
By (14): P A Z F M J G
By (4): P A Z F M J G T
By (7): P A Z F M J G T B
By (10): P A Z F M J G T B K
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