Math
If it were two hours later, it would be half as long until midnight as it would be if it were an hour later. What time is it now?
9pm
What would be warmer to wear : three shirts layered or one shirt as thick as the three together (same material) ?
Three shirts
There are three switches downstairs. Each corresponds to one of the three light bulbs in the attic. You can turn the switches on and off and leave them in any position. How would you identify which switch corresponds to which light bulb, if you are only allowed one trip upstairs?
Keep the first bulb switched on for a few minutes. It gets warm, right? So all you have to do then is ... switch it off, switch another one on, walk into the room with bulbs, touch them and tell which one was switched on as the first one (the warm one) and the others can be easily identified
A family has two kids, one of them is a girl. Assume safely that the probability of each gender is 1/2. What is the probability that the other kid is also a girl?
1/3 The following are possible combinations of two children: Girl - Girl | Girl - Boy |Boy - Girl | Boy - Boy Since we know one of the children is a girl, we will drop the Boy-Boy possibility from the sample space. This leaves only three possibilities, one of which is two girls. Hence the probability is 1/3
A Petri dish hosts a healthy colony of bacteria. Once a minute every bacterium divides into two. The colony was founded by a single cell at noon. At exactly 12:43 (43 minutes later) the Petri dish was half full. At what time will the dish be full?
The dish will be full at 12:44
A passenger train leaves New York for Boston traveling at the speed of 120 miles/hr. In half an hour a freight train leaves Boston for New York traveling at the speed of 100 miles/hr. Which train will be further from New York when they meet?
They will be same distance from NYC
You are in a room with no metal objects except for two iron rods. Only one of them is a magnet with the magnetic poles at its ends. . How can you identify which one is a magnet?
- You can hang the iron rods on a string and watch which one turns to the north (or hang just one rod). or: Take one rod and touch with its end the middle of the second rod. If they get closer, then you have a magnet in your hand. The real magnet will have a magnetic field at its poles, but not at its center. So as previously mentioned, if you take the iron bar and touch its tip to the magnet's center, the iron bar will not be attracted.
A man who lives on the tenth floor takes the elevator down to the first floor every morning and goes to work. In the evening, when he comes back; on a rainy day, or if there are other people in the elevator, he goes to his floor directly. Otherwise, he goes to the seventh floor and walks up three flights of stairs to his apartment. Can you explain why?
The man is of short stature. He can't reach the upper elevator buttons, but he can ask people to push them for him. He can also push them with his umbrella.
You've got 27 coins, each of them is 10g, except for 1. The 1 different coin is 9g or 11g (heavier, or lighter by 1g). You should use balance scale that compares what's in the two pans. You can get the answer by just comparing groups of coins. What is the minimum number weighings that can always guarantee to determine the different coin?
3 weightings - by breaking the coins in 3 equal groups each time and weighting two against each other.
A a yellow, fat-soluble vitamin,found in yellow and orange fruit and vegetables. Important for the vision function
Vitamin A
Two trains, 200 km apart, are moving toward each other at the speed of 50 km/hour each. A fly takes off from one train flying straight toward the other at the speed of 75 km/hour. Having reached the other train, the fly bounces off it and flies back to the first train. The fly repeats the trip until the trains collide and the bug is squashed. What distance has the fly traveled until its death? There is a complicated and an easy way to calculate this.
150 km. There is a complicated way counting a sequence. Or simply knowing that if the fly is flying for 2 hours still at the same speed of 75 km/h then it flies a distance of 150 km
A man in a restaurant asked a waiter for a juice glass, a dinner plate, water, a match, and a lemon wedge. The man poured enough water onto the plate to cover it. "If you can get the water on the plate into this glass without touching or moving this plate, I will give you $100," the man said. "You can use the match and lemon to do this." A few minutes later, the waiter walked away with $100 in his pocket. How did the waiter get the water into the glass?
First, the waiter stuck the match into the lemon wedge, so that it would stand straight. Then he lit the match, and put it in the middle of the plate with the lemon. Then, he placed the glass upside-down over the match. As the flame used up the oxygen in the glass, it created a small vacuum, which sucked in the water through the space between the glass and the plate. Thus, the waiter got the water into the glass without touching or moving the plate.
There are three boxes of 100 marbles each : White marbles, Black marbles, Mixed - black and white marbles. Their labels have been mixed so that no label is on its original box any longer. What is the minimum amount of marbles one needs to draw to re-establish the boxes content?
1 from the box with the "mixed" label
Which animal (including humans) has the longest memory?
Dolphins Have the Longest Memory. Forget elephants! A new study has shown that bottlenose dolphins have the longest memory in the animal kingdom.
The circumference of the Earth is approximately 40,000 km. If we made a circle of wire around the globe, that is only 10 meters (0.01 km) longer than the circumference of the globe, could a flea, a mouse, or even a man creep under it?
Yes, a shorter person could walk, a taller one would need to duck. 2pi*r = 40,000km 2pi*R = 40,000.01km R-r ~= 0.0016km = 1.6m
You awake inside a small transparent capsule sitting on the surface of Venus. From a small speaker you hear a voice that says, "We will leave you here either for a day or a year. If you choose to stay a day, we will give you $1 million. If you choose to stay a year, we will give you $2 million. Either way, you will have sufficient food and water. We will make sure the temperature is a constant 72 degrees Fahrenheit. We will also supply cable TV." What is your choice?
Choose to stay one year and win $2 million. Venus takes 243 Earth days to rotate on its axis, but it takes 225 Earth days to go around the sun. On Venus a day is longer than a year.
Three Masters of Logic wanted to find out who was the wisest among them. So they turned to their Grand Master, asking to resolve their dispute. "Easy," the old sage said. "I will blindfold you and paint either red, or blue dot on each man's forehead. When I take your blindfolds off, if you see at least one red dot, raise your hand. The one, who guesses the color of the dot on his forehead first, wins." And so it was said, and so it was done. The Grand Master blindfolded the three contestants and painted red dots on every one. When he took their blindfolds off, all three men raised their hands as the rules required, and sat in silence pondering. Finally, one of them said: "I have a red dot on my forehead." How did he guess?
The wisest one must have thought like this: I see all hands up and 2 red dots, so I can have either a blue or a red dot. If I had a blue one, the other 2 guys would see all hands up and one red and one blue dot. So they would have to think that if the second one of them (the other with red dot) sees the same blue dot, then he must see a red dot on the first one with red dot. However, they were both silent (and they are wise), so I have a red dot on my forehead.
A physiological feature that only humans, chimps, gorillas, and koalas have on their hands
Fingerprints
Replace the "?" by the correct Mathematics symbol to make the expression true 18 ? 12 ? 4 ? 5 = 59
18 * 12 / 4 + 5
One is the acceleration an object experiences as it travels a certain velocity along an arc. It points towards the center of the arc. Other is the imaginary force an unrestrained object experiences as it moves around an arc. This force acts opposite to the direction of the first one. For example, if a car makes a sharp right turn the passengers would tend to slide in their seats away from the center of the turn, towards the left.
The centripetal acceleration and centrifugal forces
Name two properties of protein side chains that give clues to their folded position.
Hydrophobic/Hydrophilic, Positively Charged/Negatively Charged.