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Puzzle:
"If you were to put a coin into an empty bottle and then insert a cork in the bottle's opening, how could you remove the coin without taking out the cork or breaking the bottle? "
- The keypoint is quite simple ---> why can't we just push cork inside the bottle, pour out the liquid inside and take out the coin?
Puzzle:
"Speaker: "Brothers and Sisters, I have none. But this man's Father is my Father's son. Who is the speaker talking about? "
- The speaker is talking about his own son.
Puzzle:
"An analog clock reads 3:15. What is the angle between the minute hand and hour hand? "
- We think about the problem in the following way:
- at 3:00, the angle between the minute hand and hour hand is just 90 ---> the minute hand is at 12, and the hour hand is at 3.
- the velocity of minute hand per minute: 360 / 60 = 6 degrees
- the velocity of hour hand per minute: 30 / 60 = 0.5 degrees
- at 3:15: 90 + 0.5 * 15 - 6 * 15 = 7.5 degrees
Puzzle:
"Imagine an analog clock set to 12 o'clock. Note that the hour and minute hands overlap. How many times each day do both the hour and minute hands overlap? How would you determine the exact times of the day that this occurs? "
- Actually, we don't need to do any calculaion if we only consider the number of times of meeting. ---> I think of this point after doing some calculations...
- We know: the minute hand moves more quickly than the hour hand, so in the first cycle, the two hands will not meet.
- the minute hand will finish the 360 degrees without intersecting with hour hand.
- However, starting at the second circle, the two hands will always meet in each cycle:
- the minute hand will go over 360 degrees, while the hour hand will only go over 30 degrees each cycle.
- If we split the 12 hours in daytime and 12 hours in night into two parts, we will find that in the first 12 hours, the last time the two hands meet are at 12.
- that starts at 11 o'clock, and as the hour hand reaches 12, the minute hand reaches 12 two.
- the two hands only don't meet in the first cycle ---> in total, they meet 11 times.
- For the other 12 hours, it is just a repeated process, and the two hands will still meet 11 times.
- in 24 hours, they will meet 22 times in total.
Puzzle:
"There are three closed and opaque cardboard boxes. One is labeled "APPLES", another is labeled "ORANGES", and the last is labeled "APPLES AND ORANGES". You know that the labels are currently misarranged, such that no box is correctly labeled. You would like to correctly rearrange these labels. To accomplish this, you may draw only one fruit from one of the boxes. Which box do you choose, and how do you then proceed to rearrange the labels? "
- We just draw one fruit from the box with "APPLE AND ORANGE".
1. If it is apple, then we are left with orange / apple & orange
- now we have two boxes, one is
