Interview Questions
Puzzles
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Using the ciphers 1 up to 9, three numbers (of three ciphers each) can be formed, such that the second number is twice the first number, and the third number is three times the first number. Which are these three numbers? |
| Ans:
There are two solutions: |
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Julius and Vincent are brothers. "We are born within the same hour," says Julius, "on the same day of the same year." "But," says Vincent, "we are no twins!" How is this possible? |
| Ans:
Julius and Vincent are part of a set of triplets, or quadruplets, or even more. |
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The poor have it, the rich want it, but if you eat it you will die. What is this? |
| Ans:
Nothing! . |
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In the Tour de France, what is the position of a rider, after he passes the second placed rider? |
| Ans:
Second!. |
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In Miss Miranda's class are eleven children. Miss Miranda has a bowl with eleven apples. Miss Miranda wants to divide the eleven apples among the children of her class, in such a way that each child in the end has an apple and one apple remains in the bowl. Can you help Miss Miranda? |
| Ans:
Ten children get a single apple, and the eleventh gets the bowl with an apple still in it. |
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Hans is standing behind Gerrie and at the same time Gerrie is standing behind Hans. How is this possible? |
| Ans:
Hans and Gerrie are standing with their backs towards each other!. |
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Of all the numbers whose literal representations in capital letters consists only of straight line segments (for example, FIVE), only one number has a value equal to the number of segments used to write it. Which number has this property? |
| Ans:
This is the only solution that satisfies the requirement that the capital letters shall consist only of straight line segments. |
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A snail is at the bottom of a 20 meters deep pit. Every day the snail climbs 5 meters upwards, but at night it slides 4 meters back downwards. How many days does it take before the snail reaches the top of the pit? |
| Ans:
On the first day, the snail reaches a height of 5 meters and slides down 4 meters at night, and thus ends at a height of 1 meter. Conclusion: The snail reaches the top of the pit on the 16th day!. |
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You walk upwards on an escalator, with a speed of 1 step per second. After 50 steps you are at the end. You turn around and run downwards with a speed of 5 steps per second. After 125 steps you are back at the beginning of the escalator. How many steps do you need if the escalator stands still? |
| Ans:
Let v be the speed of the escalator, in steps per second. Let L be the number of steps that you need to take when the escalator stands still. Upwards (along with the escalator), you walk 1 step per second. You need 50 steps, so that takes 50 seconds. This gives: L - 50 × v = 50. Downwards (against the direction of the escalator), you walk 5 steps per second. ,You need 125 steps, so that takes 25 seconds. This gives: L + 25 × v = 125. From the two equations follows: L = 100, v = 1. When the escalator stands still, you need 100 steps. |
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On a sunny morning, a greengrocer places 200 kilograms of cucumbers in cases in front of his shop. At that moment, the cucumbers are 99% water. In the afternoon, it turns out that it is the hottest day of the year, and as a result, the cucumbers dry out a little bit. At the end of the day, the greengrocer has not sold a single cucumber, and the cucumbers are only 98% water. How many kilograms of cucumbers has the greengrocer left at the end of the day? |
| Ans:
In the morning, the 200 kilograms of cucumbers are 99% water. So the non-water part of the cucumbers has a mass of 2 kilograms. At the end of the day, the cucumbers are 98% water. The remaining 2% is still the 2 kilograms of non-water material (which does not change when the water evaporates). If 2% equals 2 kilograms, then 100% equals 100 kilograms. ,So, the greengrocer has 100 kilograms of cucumbers left at the end of the day. |