Puzzle 81
If I can boil 2 eggs in 10 minutes.
How long will it take me to boil 5 eggs?
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Hint
Be careful with your thinking.
Answer
Exactly the same time!
Puzzle 82
By changing the second letter of each of the words below, can you make another valid word?
You have to change each word such that the second letters will reveal a ten-letter word when read downwards.
Therefore, what now reads 'craihruane' will be a real word.
icon
crew
farm
oily
chop
arid
fund
wait
gnat
tear
Puzzle Copyright © Kevin Stone
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Hint
The 9th word is GOAT.
Answers
Rhinoceros.
iron
chew
firm
only
coop
acid
fend
writ
goat
tsar
Puzzle 83
Which of the four shapes comes next in this sequence:
Puzzle Copyright © Elliott Line
This puzzle appeared in Mensa's EnigmaSig (193.06) and is used with permission.
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Hint
Perhaps looking around the shapes will help.
Answer
C.
Reasoning
The shapes are the spaces between the digits in the numbers 27, 28, 29, and 30, therefore C is the correct answer, as it is the space between the digits in the number 31.
Puzzle 84
How many people must be at a party before you are likely to have two having the same birthday (but not necessarily the same year)?
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Answer
23.
Reasoning
By likely, we mean greater than 50% chance.
With one person there is a 0 percent chance that you'll have two people with the same birthday.
With two people the probability that they won't share a birthday is 364 / 365. The probability that they will share a birthday is therefore 1 - (364 / 365).
With three people the probability that they won't share a birthday is the same as for two people, times 363 / 365. So the probability that three people will share a birthday is 1 - (364 / 365) x (363 / 365).
Notice that with each additional person added, the probability that they shares a birthday with one of the previous persons goes up, because there are fewer "free" days remaining.
We keep adding people until the %age is greater than 50%.
When we have 23 people the %age is 50.729%.
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