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Here are 4 puzzles of varying degrees of difficulty:
1.1: There are 4 people who are to cross a bridge. The bridge can hold a max of 2 persons at a time and since it is night, they need to carry a lamp with them to cross. They have just 1 lamp between them and they individually take 1, 2, 7 & 10 mins to cross the bridge alone.
What's the least amount of time they need to cross the bridge? (Hint: It's not 21 mins!)
1.2: Two ladders form a rough X in a narrow alley. They are 11
and 13 feet long and cross 4 feet off the ground.
How wide is the alley ?
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1.3 Can you tell ?
Dad wants 1-cent, 2-cent, 3-cent, 5-cent and 10-cent stamps. He wants
4 each of two sorts and 3 each of the others, but I forget which. He
gave me some dimes (10-cent coins) which are just enough to buy them.
Can you tell how many stamps of each type he wants ?
1.4 The Dating Game
Sally and Sue want to date Sam. The 3 live on the same street, with
house numbers from 1 to 99. Sally asks Sam, "Is your house number a
perfect square ?". He answers. Then she asks, "Is it > 50 ?". He
answers again. Sally thinks she now knows where Sam lives and visits
that house, only to find she is wrong. This is because Sam answered
only the 2nd question truthfully.
Unaware of this conversation, Sue asked Sam, "Is your house number a
perfect cube ?". He answers. Then she asks, "Is it > 25 ?". He
answers. Sue thinks she knows where Sam lives and visits that house,
only to find she is wrong. Again, this is because Sam answered only
the 2nd question truthfully.
Sam's house number is less than Sally's or Sue's, and the sum of their
house numbers is a perfect square multiplied by 2.
What are their house numbers ?
Dad wants 1-cent, 2-cent, 3-cent, 5-cent and 10-cent stamps. He wants
4 each of two sorts and 3 each of the others, but I forget which. He
gave me some dimes (10-cent coins) which are just enough to buy them.
Can you tell how many stamps of each type he wants ?
1.4 The Dating Game
Sally and Sue want to date Sam. The 3 live on the same street, with
house numbers from 1 to 99. Sally asks Sam, "Is your house number a
perfect square ?". He answers. Then she asks, "Is it > 50 ?". He
answers again. Sally thinks she now knows where Sam lives and visits
that house, only to find she is wrong. This is because Sam answered
only the 2nd question truthfully.
Unaware of this conversation, Sue asked Sam, "Is your house number a
perfect cube ?". He answers. Then she asks, "Is it > 25 ?". He
answers. Sue thinks she knows where Sam lives and visits that house,
only to find she is wrong. Again, this is because Sam answered only
the 2nd question truthfully.
Sam's house number is less than Sally's or Sue's, and the sum of their
house numbers is a perfect square multiplied by 2.
What are their house numbers ?
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