• # Brain Teasers & Puzzles

Questions Per Page:
• The number of hours left today is half of the number of hours already passed. What time is it?
A. 8:00 a.m.
B. 12:00
C. 14:00
D. 16:00

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ravi Expert
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• Here is snippet of section A of the curious multiple-choice entrance exam into the exclusive Puzzlefry puzzle club.

1. The first question with B as the correct answer is:

A. 1
B. 4
C. 3
D. 2

2. The answer to Question 4 is:

A. D
B. A
C. B
D. C

3. The answer to Question 1 is:

A. D
B. C
C. B
D. A

4. The number of questions which have D as the correct answer is:

A. 3
B. 2
C. 1
D. 0

5. The number of questions which have B as the correct answer is:
A. 0
B. 2
C. 3
D. 1

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ravi Expert
• 1,148.4K views

• After the recent Puzzle  annual marathon, the judges were comparing notes to determine who finished where. From their notes, can you help them to reconstruct the final result?

• Matthew Merryman beat Tom Trent and Jimmy James.
• Peter Piper beat Jimmy James, Tom Trent and Alan Ardman.
• Zach Zebra lost to Peter Piper.
• Graham Goodfellow beat Tom Trent
• Zach Zebra beat Frank Flintbone.
• Graham Goodfellow lost to Frank Flintbone and Peter Piper.
• Tom Trent beat Brian Brick.
• Alan Ardman beat Zach Zebra, Kevin Kingfisher and Graham Goodfellow.
• Kevin Kingfisher lost to Graham Goodfellow and Matthew Merryman.
• Brian Brick beat Kevin Kingfisher.
• Matthew Merryman lost to Alan Ardman and Zach Zebra.
• Frank Flintbone beat Tom Trent, Matthew Merryman and Brian Brick.
• Tom Trent lost to Jimmy James and Alan Ardman.
• Jimmy James beat Graham Goodfellow and Brian Brick.
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ravi Expert
• 1,147.6K views

• At the recent spring fete, four keen gardeners were displaying their fine roses.

In total there were four colours and each rose appeared in two colours.

From the clues below can you tell who had which colour roses?

• Mr Green had a yellow rose.
• Mr Yellow did not have a red one.
• Mr Red had a blue rose but not a green one.
• Mr Blue did not have a yellow one.
• One person with a red rose also had a green one.
• One person with a yellow rose also had a blue one.
• One of the persons with a green rose had no red.
• Neither of the persons with a yellow rose had a green one.
• No person has two roses of the same colour.
• No two persons had the same two colour roses and their names provide no clues.
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ravi Expert
• 1,148.1K views

• Puzzlefry bought 2 teapots,

If teapot A holds 32 cups of tea, about how many cups of tea does teapot B hold?

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• 1,157.5K views

• A king wants an advisor and comes to ask the 3 wisest sages.

He blindfolds them and put the hats on their head. Afterwards, the king takes off their blindfolds. He tells them that their hat is either blue or white. He tells them that whoever can deduce the color of their hat will be his next advisor. Also he tells them that at least one of the sages will be wearing a blue hat. The sages can all see each other’s hats except of course, their own. Sage A sees that the other 2 are wearing blue hats.
For hours no one spoke, then Sage A stands up and tells the  king the colour of his hat. What color is it and how does he know?

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Albert Scholar
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Albert Scholar
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• This was the second problem for Google Code Jam Qualification round 2014, if you are able to solve this problem with the first one(which is very easy) you will be eligible for the next round.

### Problem

Once you have X cookies that you haven’t spent on farms, you win! Figure out how long it will take you to win if you use the best possible strategy.

### Example

Suppose C=500.0, F=4.0 and X=2000.0. Here’s how the best possible strategy plays out:

1. After 250 seconds, you will have C=500 cookies and can buy a farm that producesF=4 cookies per second.

1. Another farm will cost 500 cookies, which you can buy after 50 seconds.

1. Another farm would cost 500 cookies, but it actually makes sense not to buy it: instead you can just wait until you have X=2000 cookies, which takes about142.8571429 seconds.

Total time: 250 + 83.3333333 + 50 + 142.8571429 = 526.1904762 seconds.

Notice that you get cookies continuously: so 0.1 seconds after the game starts you’ll have 0.2 cookies, and π seconds after the game starts you’ll have 2π cookies.

### Input

The first line of the input gives the number of test cases, TT lines follow. Each line contains three space-separated real-valued numbers: CF and X, whose meanings are described earlier in the problem statement.

CF and X will each consist of at least 1 digit followed by 1 decimal point followed by from 1 to 5 digits. There will be no leading zeroes.

### Output

For each test case, output one line containing “Case #x: y”, where x is the test case number (starting from 1) and y is the minimum number of seconds it takes before you can have X delicious cookies.

We recommend outputting y to 7 decimal places, but it is not required. y will be considered correct if it is close enough to the correct number: within an absolute or relative error of 10-6. See the FAQ for an explanation of what that means, and what formats of real numbers we accept.

### Limits

1 ≤ T ≤ 100.

#### Small dataset

1 ≤ C ≤ 500.
1 ≤ F ≤ 4.
1 ≤ X ≤ 2000.

#### Large dataset

1 ≤ C ≤ 10000.
1 ≤ F ≤ 100.
1 ≤ X ≤ 100000.

### Sample

 Input Output ```4 30.0 1.0 2.0 30.0 2.0 100.0 30.50000 3.14159 1999.19990 500.0 4.0 2000.0``` ```Case #1: 1.0000000 Case #2: 39.1666667 Case #3: 63.9680013 Case #4: 526.1904762```

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Albert Scholar
• 1,148.2K views

• You are trying to cook an egg for exactly fifteen minutes, but instead of a timer, you are given two ropes which burn for exactly 1 hour each. The ropes, however, are of uneven densities – i e , half the rope length-wise might take only two minutes to burn. How can you cook the egg for exactly fifteen minutes?

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Albert Scholar
• 1,149.6K views

• On Bagshot Island, there is an airport. The airport is the homebase of an unlimited number of identical airplanes. Each airplane has a fuel capacity to allow it to fly exactly 1/2 way around the world, along a great circle. The planes have the ability to refuel in flight without loss of speed or spillage of fuel. Though the fuel is unlimited, the island is the only source of fuel.
What is the fewest number of aircraft necessary to get one plane all the way around the world assuming that all of the aircraft must return safely to the airport? How did you get to your answer?

Notes:
(a) Each airplane must depart and return to the same airport, and that is the only airport they can land and refuel on ground.
(c) The time and fuel consumption of refueling can be ignored. (so we can also assume that one airplane can refuel more than one airplanes in air at the same time.)
(d) The amount of fuel airplanes carrying can be zero as long as the other airplane is refueling these airplanes. What is the fewest number of airplanes and number of tanks of fuel needed to accomplish this work? (we only need airplane to go around the world)

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• ## More puzzles to try-

• ### Unique Gatsby riddle

Given below paragraph a unique in something. Find out the uniqueness in this ? “Gatsby was walking back from a ...Read More »
• ### Spiders in Silicon Valley riddle

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• ### Connect all 9 of the dots

Connect all 9 of the dots using 4 straight lines or less. Do so without lifting the pen or tracing ...Read More »
• ### Which of the statements is true?

A. The number of false statements here is one. B. The number of false statements here is two. C. The ...Read More »
• ### Ek Gali Mein Bachay Khel Rahay Thae riddle

Only 1 hindi word fits all the Blanks, What is that word ? Hindi in English- Ek Gali Mein _____ ...Read More »
• ### Sciencetific trick puzzle

You are lying on a beach with a wine bottle enjoying the bright sun. After it goes empty, your friend ...Read More »
• ### Can you see the Cat?

Can you find the Cat in the picture puzzleRead More »
• ### who answer first riddle

a Judge decided to freed Four criminals without any punishment but after solving a puzzle, as it was a minor ...Read More »
• ### Tricky Maths Equation

Can you solve this tricky maths equation problem by replacing it? mark with the correct symbol? 19834 —–: 187 15921 ...Read More »
• ### DEATH MATCH PUZZLE

You have just arrived to Wild West and you have already got in trouble. Buffalo Bill and Killer Kid are ...Read More »
• ### How much dirt is in a hole

How much dirt is in a hole that has a radius of 33.2 meters and a height of 78.2 meters?Read More »
• ### Lateral thinking sequence Puzzle

Solve this logic sequence puzzle by the correct digit- 8080 = 6 1357 = 0 2022 = 1 1999 = ...Read More »
• ### Sphere, Circle & Zero

A sphere has three, a circle has two, and a point has zero. what would we call it ?Read More »
• ### Why johnny is not wrong?

Little Johnny’s teacher asks him, “If I gave you two cats, then two more, and two more cats; how many ...Read More »
• ### How does he successfully cross the river with his load?

A man needs to cross a river in a canoe.  With him, he has a bag of grain, a chicken, ...Read More »
• ### digit puzzle

What 5 digit number am I thinking of. It has two prime digits. Digit 3 is the highest digit. Digit ...Read More »
• ### Eye Puzzle

This rectangle of seemingly random colored dots contains a message. Do you know the answer?Read More »
• ### Probability of having boy

In a country where everyone wants a boy, each family continues having babies till they have a boy. After some ...Read More »
• ### Musical Animal

It is a fruit. If you take away the first letter of its name it becomes a crime. Take away ...Read More »
• ### Three house puzzle

There are 3 houses black, red and white . The black one is in the north ,the red one is ...Read More »