Brain Teasers and Puzzles

Continue the sequence : 3/3 = 5/3 = 1/5 = 10/5 = 8/4 = 6/4 = 4/6 = 100/ ? a) 3 b) 20 c) 50 d) 100 e) 200 f) 500

1, 21, 18, 27, ?, 2, 14, 11, 28, ?

What rhymes with "false"?

I was reminiscing about a problem that my Calculus 3 professor gave us, and decided to modify the problem to make it a little more challenging to solve. Although the problem isn't hard to figure out, it does have some interesting consequences. So without further adieu, I give you my ninth challenge. A Moth to a Flame It is common knowledge that certain insects, such as moths, are attracted to light sources. Let's consider that a moth navigates the world by maintaining a constant angle to the sun, which can be considered an infinite light source. Furthermore, let's say that at night the moth uses any light source that is available, and for all intents and purposes our li…

For this challenge, I decided to go with something most everyone is familiar with, the parabola. Given that [math]y=a x^2 + b x + c[/math], the goal of this challenge is to find the parabolas that reach a height of [math]h[/math], and go through the points, [math]P_1=\{x_1,\ y_1\}[/math] and [math]P_2=\{x_2,\ y_2\}[/math]. All of the variables have been specified, and although this challenge may seem easy, I assure you that it is quite difficult. Reputation awaits the one who can provide the solution for this challenge first.

After a cursory glance on here, I don't see any threads about this. Has anyone heard of Weff Riddles? It's basically a series of riddles (not entirely sure you could call them that), where you type the correct answer in the section of the url between ".com" and ".html". If you get the answer right, you move on to the next level. If it's wrong, then you are shown a page giving a suggestion as to a way to correct your answer. In the spirit that the creator is trying to keep with the original riddle, please don't post any spoilers in this thread. I'm just trying to introduce people to it. Mods, if someone does post a spoiler/answer, please remove/sensor it...

Can someone give me tricks in memorizing activity series of the elements or the solubility chart? Or any simple tricks that is very interesting about science or maths that could help me in the future I would be thankful if someone can give me any tricks.

Infer the color of each of the four (?) spaces. You need no other information that what is given. For the first row (red, red, orange, orange) One of these is the correct color and in the correct place, you just don't know what. The other three are wrong. For the second row (green, blue, blue, green) Two are the correct color and in the correct place and one is the correct color but in the wrong place. You get the idea. If you want to play more you can go to T H I N K

There are 16 [off]switches that can be activated by passing a laser beam into them.Using 5 mirrors and a laser gun , how can you switch them all [on] with one shot? O O O O O O O O O O O O O O O O Please use

There are only 16 fundamental logical operators which describe the fundamental relationship between any two arguments. That is if A is true and B is false then C is false. This is consistent with the logical operator AND, but it is also consistent with the logical operator NOR. The difference between the two lies in their response to the other permutations of A and B. Can you use the logical operator NOR to describe the relationship between the sensors and actuators in this simulation of a swinging ball? Use three NOR gates to connect the sensors to the actuator so that the pin ball is launched upwards at exactly the time needed for the swinging soccer ball to …

In my sixth challenge, which is based upon the Collatz conjecture, I found a way to determine the odd numbers that reduce to one given a count of the odd numbers within their Hailstone sequences. The reason why I focused my efforts on odd numbers is because all even numbers will reduce to an odd number by dividing it by two until an odd number is reached. As I was analyzing the sequence of exponents generated by recursively dividing even numbers by two, I noticed an interesting pattern and derived a formula to predict these exponents. Not only did I discover how to predict powers of two, but also for any other factor as well. The following image shows the exponents for fa…

CiSRA puzzle competition is open for another year, so I thought I'd post a favourite from last year's puzzles. I've attached the PDF, but this is the text version of the puzzle (it's solvable either way): Why, I belgeve ther're my few remaining years erieving for the loss special occasion, af course. I tas a you haven't been keepsng up on current events, bht we just is you're not the only ono. You don't love me! He'lt come back here. As I'vk pinched his lahdh key, th'll try animal you've trapped! Waen you decide of betttng weren't scientipic, but teey they don't aell you in ahe church. You ere illegally you'll be nead and I'll blow this place up and be oome in to mot…

Have a look at this riddle. I've never seen anything quite like it, and I am a collector of math puzzles and brain teasers. See if you can solve it without reading the solution (at the bottom of the link). I guess there is a slight hint given in the explanation, and that is that a solution involves the axiom of choice.

It has been a long time since I've posted one of my challenges. The reason is not because a lack of time. Instead, I am running out of problems that can be considered interesting or at least require some skill in solving mathematical puzzles. Sure, I could try to find something on the internet, but I don't want you to be able to simply look up the answer, and I want the problems to really make you think about possible solutions so that you discover something new for yourself, which is way more rewarding than having someone teach you math. For those of you that have never seen them, here are the links to my previous challenges (the first challenge is my favorite, but I al…

There are 5 different people in the same vicinity who all know that each other person is observing them. Each person has a different color marked on their forehead which they do not know the color of but that every other person can see. If any person sees three blue marks, they are to stand up. And, if anyone knows the color on their forehead, they raise they're hand. The person who raises their hand first wins the prize. The people cannot intentionally communicate which each other in any way and the person running the test does not communicate with any person in any way. Shortly after the timer starts, 3 people stand up, but shortly after that, one person raises their h…

Come up, bring your explanation. ----->

I don't know where I get this question I found it in my laptop. I think it is very nice. How could you cut a hole in a 3 by 5 card that is big enough for you to put your head through?

So for this story, God created man. But, all the body parts were arguing over who gets to be the boss. The brain says "I get to be the boss because I do almost all of the thinking". The arm says "No I should be the boss because without me you can't do anything". The stomach says "No I'm the boss because without me you'd starve". The body parts keep arguing and finally the butt or a§§ says "No, I'm the boss". The other body parts laugh at him, so the butt goes on strike and closes up. Finally after a few days the other body parts can't take it and let him be boss. What is the moral of this story?

There are 10bags each containing 10 weights,all of which look identical.In 9 of the bags each weight is 16 ounces,but in one of the bags the weights are actually 17 ounces each.How is it possible in a single weighing on an accurate weighing scale to determine which bag contains the 17-ounce weights?

The classic problem of a monkey and the greased flag pole. The height of a certain flag pole is 30 feet. Grease is applied to the pole. A monkey attempts to climb the pole. It climbs 3 feet every second but slips down 2 ft in the next second. When will the monkey reach the top of the flag pole? 56 seconds 27 seconds 60 seconds 55 seconds

A woman has two children. After talking with her for a while, you figure out that at least one of them is a daughter. Assuming any given child has a 50-50 chance of being a girl, what is the probability of both children being girls? Now, you keep talking to her and you're able to figure out that this girl is the youngest child. Does the probability that they're both girls change? If so, what's the new probability?

Came across this interesting problem on the Feynman Lectures site. The answer is there, so no peeking!

A farmer (on an island of course) has 100 cows in a barn. Each is brown or blue, and each was purchased from a supplier that randomly sells a brown or a blue cow with equal likelihood. A cow escapes from the barn and it is brown. What is the expected proportion of brown cows to total cows?

http://www.englishforums.com/English/EinsteinsRiddleFish/bhvj/post.htm Don't write the answer to the riddle in the comments, just write Howe long it took you, or if you gave up, be honest This has probably been done on here before but i'm new so you'll have to excuse me please I'll go first, it took me just under ten minutes and a page of working it out, I got there but not with ease Good luck

Hi. Anybody free to help me understand this one? First image: 11 40 23 16 --> 18 Second image: 10 21 33 50 --> ? ------ Thanks