Puzzle 17
A large freshwater reservoir has two types of drainage system. Small pipes and large pipes.
6 large pipes, on their own, can drain the reservoir in 12 hours.
6 small pipes, on their own, can drain the reservoir in 18 hours.
How long will 6 large pipes and 6 small pipes take to drain the reservoir?
Puzzle Copyright © Kevin Stone
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Hint
How many reservoirs can each drain in 36 hours?
Answer
7 hours and 12 minutes.
Reasoning
We can use a time that 12 hours and 18 hours both fit in to, in 36 hours:
6 large pipes can drain 3 reservoirs.
6 small pipes can drain 2 reservoirs.
Therefore, together, 6 large and 6 small pipes can drain 5 reservoirs.
36 hours ÷ 5 = 7.2 hours for one reservoir.
7.2 hours = 7 hours and 12 minutes for one reservoir.
Puzzle 18
Last week I spent half of my money on a new jacket, and then I spent half of that amount on some new trousers.
I was left with £32.94. How much did I spend?
Puzzle Copyright © Kevin Stone
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Hint
Try working backwards.
Answer
£98.82.
Reasoning
At the end I was left with £32.94, which was half of my remaining money, so before buying the trousers I must have had £65.88.
Again, this was half of my money, so before buying the jacket I must have had £131.76 at the start.
As I now had £32.94 remaining, I must have spent £98.82.
Double-Checking
I started with £131.76, and I spent £65.88 on a new jacket, and then £32.94 on the trousers, a total spend of £98.82.
Puzzle 19
You can replace the dashes with the same four-letter word, and create two new words, one that starts with ARM, and one that ends in ING.
Can you find all possible four-letter words that work?
arm----
----ing
Puzzle Copyright © Kevin Stone
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Hint
There are 4 possible answers.
Answer
Band, load, lock, and rest, all create new words:
armband and banding
armload and loading
armlock and locking
armrest and resting
Note
Some dictionaries also allow ARMRACK, but others don't. So RACK is a unofficial possible answer.
Puzzle 20
hwayetritipzl
omnltesnhsuze
Puzzle Copyright © Kevin Stone
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Hint
The puzzle contains the question.
Answer
26.
Reasoning
The puzzle reads 'how many letters in this puzzle'.
The puzzle's letters alternate between the top and bottom lines.
