#1 - Card Riddle

I have mixed 13 decks of cards.
What is the minimum number of cards must be taken out from the above mixed cards to guarantee at least one 'four of a kind'.

Card Riddle
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13 x 3 + 1 = 40

Explanation:

The number of decks is irrelevant i.e any number of decks can be mixed and still the answer would be same.
Any card drawn will be a Ace,2,3,4,5,6,7,8,9,10,Jack,Queen or King, so there are 13 possibilities each time a card is drawn.
The fastest and luckiest way would need just 4 cards of the same kind.

The slowest way is our solution as it will guarantee a four of a kind.
i.e draw 3 of each kind =>39 cards will be fetched. now next card will guarantee 4 of a kind.

#2 - Building Puzzle

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

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20
Just count the nines in the numbers: 9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99.
Note: 99 contains TWO nines!

#3 - Puzzle Boat

At the local model boat club, four friends were talking about their boats.

There were a total of eight boats, two in each colour, red, green, blue and yellow. Each friend owned two boats. No friend had two boats of the same colour.

Alan didn't have a yellow boat. Brian didn't have a red boat, but did have a green one. One of the friends had a yellow boat and a blue boat and another friend had a green boat and a blue boat. Charles had a yellow boat. Darren had a blue boat, but didn't have a green one.

Can you work out which friend had which coloured boats?

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Alan had a red boat and a green boat.
Brian had a green boat and a blue boat.
Charles had a yellow boat and a red boat.
Darren had a blue boat and a yellow boat.

#4 - Cross The Desert Logical Riddle

Mr. Rawat wishes to cross a the Sahara desert.
It requires 6 days to cross.
One man can only carry enough food and water for 4 days.

What is the fewest number of other men required to help carry enough food for Mr. Rawat to cross ?

Cross The Desert Logical Riddle
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2men

Say 2 helpers are A & B
A food B food Rawat's Food
End of Day 1 : 1 4 4
Now 'A' will head back

End of Day 2 : N/A 2 4
Now 'B' will head back

Now Mr. Rawat have 4 day food :-)

#5 - Infineon Logic Interview Question

I purchased an awesome ice cream cone having 5 different flavor scoop.
Five flavors are pistachio, mint-chip, strawberry, marshmallow, and raspberry

I will give u some clues so that you can figure out the order of flavors from bottom to top.
1. The bottom flavor of the cone has 10 letters.
2. The marshmallow scoop is at between pistachio and the mint-chip scoop.
3. marshmallow is the raspberry scoop but below the mint-chip scoop.

So can you figure out the flavor of ice cream in order from bottom to top

Infineon Logic Interview Question
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From bottom to top, the flavors are :

Strawberry
raspberry
pistachio
marshmallow
mint-chip

#6 - Logic Puzzle Problem

Like an usual car, my new i10 car has 5 wheels(2 front + 2 Rear + 1 spare).
The rear wheel of the car will wear out after 21000 kilometers and the front wheel will wear out after 29000 kilometers.

What is the maximum distance I can cover assuming changing of wheels is not an issue?

Logic Puzzle Problem
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Maximum distance: 30,450 kilometers.

For every 5 kilometers driven using this rotation, each tire will lose (2/29000)+(2/21000) of its tread.So, suppose we drive 5*N kilometers like this. Then, each tire will lose 2*N*((1/29000)+(1/21000)) of its tread. We wish to determine N so that the latter expression gets to be 1, representing all of each tire's tread. That happens when N=6090, which is when 5*N (the total kilometers were driven) is 30,450.

#7 - Murder Mystery Problem

One evening there was a murder in the home of married couple, their son and daughter. One of these four people murdered one of the others. One of the members of the family witnessed the crime.

The other one helped the murderer.

These are the things we know for sure:

1. The witness and the one who helped the murderer were not of the same sex.

2. The oldest person and the witness were not of the same sex.

3. The youngest person and the victim were not of the same sex.

4. The one who helped the murderer was older than the victim.

5. The father was the oldest member of the family.

6. The murderer was not the youngest member of the family.

Who was the murderer?

Murder Mystery Problem
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mother

We know from (3) that the youngest person was not the victim, from (4) that the youngest person was not the helper and from (6) that the youngest person was not the killer. The youngest person can only have been the witness therefore. If we make up a chart there are now three possible combinations:

Oldest person (father) H H M

Next to oldest (mother) V M H

Next to youngest (son) M V V

Youngest (daughter) W W W

(H = Helper ; V = Victim ; M = Murderer ; W = Witness)

We can work out from (5) that the father was the oldest, from (2) that the youngest person must have been the daughter. Therefore the next to the youngest must have been the son and the next to the oldest, the mother.

Of three possibilities: the first is impossible (from (3) – the youngest person and the victim were of different sexes); the third is also impossible (from (1) – the witness and the helper were of different sexes). Therefore only the second possibility holds – and the mother was the murderess.

#8 - King Gift Puzzle

King Charles want to send the diamond ring to his girlfriend securely.He got multiple locks and their corresponding keys.His girl friend does not have any keys to these locks and if he send the key without a lock , the key can be copied in the way.How can charles send the ring to his girl friend securely .

King Gift Puzzle
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charles put the ring into the box, secure it with one of your locks, and send the box to the girl firend.
She should then attach one of his own locks and return it. When you receive it again, remove your lock and send it back with her lock. Now she can unlock his own lock and retrieve the object.

#9 - Easy Logic Problem

My sock drawer has 26 blue socks, 13 pink socks, 33 green socks, and 12 red socks, how many socks would I have to pull out in the dark to be sure i had a matching pair?

Easy Logic Problem
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Five. There are only four colors, so five socks guarantee that two will be the same color.

#10 - Mathematical Logic Puzzle

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

Mathematical Logic Puzzle
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188 - 88