Math puzzles haven't really been all that popular around here. It makes sense - I mean, who wants to get off from class just to do more work? Just kidding. Do a search for math and you'll see tons of random math quizzes all around the place. Well, when there's a prize involved, I suppose that's enough of an incentive. Chour has involved math with several of his puzzles, but I dont believe any of his quizzes are entirely math based. There are plenty of other users that have made math puzzles as well, and I'm not going to lay them all down here. I have noticed, however, that none of the quizzes ever get more complicated than simple calculus. I think one day I'll go into complex analysis, but today is not that day.

Instead, take some simple probabilities

Rules:
Do not share answers, hints, giveaway links, the name of the giveaway or generally spoil the puzzle in any form.

If you solve at least half (15) of the puzzles, you will get an invite to a private giveaway when the A Puzzle a Day series concludes. I'll try to pick something that no one has already, but no guarantees. Please make a parent post in the giveaway to be counted. Also, to be invited to the bonus giveaway, post in A Puzzle a Day #30 with the puzzles you have solved. You are not required to solve the puzzles before the giveaways end. Solving them at any point in time will count towards the 15 required puzzles.

Solution:

1. When you enter, there are 100 entries total, so you have a 1/100 chance to win = 1.0000%

2. Let P(W) be the chance you win and P(L) be the chance you lose. The chance to win at least one is defined as
P(At least one) = 1- P(L)^3 = 5.88080%

3. The chance to win exactly one is defined as the chance to win giveaway #1 but not #2 or #3 plus the chance to win giveaway #2 but not #1 or #3 plus the chance to win giveaway #3 but not #1 or #2.

P(exactly one) = P(W)P(L)P(L) + P(L)P(W)P(L) + P(L)P(L)P(W) = (P(W)P(L)P(L))^3 = 5.76240%

4. Chance that you will win all three is defined as

P(all three) = P(W)^3 = 0.00080%

5. This is similar to question 3, but only take the first term

P(only first) = P(W)P(L)P(L) + P(L) = 1.92080%

6. Let H be the event that you enter and N be the event that you don't. Then let D, S, and W be the event that the giveaway is real, the giveaway is deleted by the mods, and the giveaway is deleted by the giveaway owner, respectively. We are given the following:

P(H) = .9, P(N) = .1
P(D|N) = .8, P(S|N) = .2, P(W|N) = 0
P(D|H) = .65, P(S|H) = .2, P(W|H) = .15

The probability that that the giveaway is real is given by

P(real) = P(D|H)P(H) + P(D|N)P(N) = 66.50000%

And thus the probability that the giveaway is deleted is

P(deleted) = 1 - P(real) = 33.50000%

7. This is just a simple application of Bayes Theorem

P(N/D) = P(D/N)P(N) / P(D) = 12.00000%

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Math @___@~

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TOO HARD!

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Hooray math! ...but I can't figure out the format...

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Answer should be in [However many before the decimal].XXXXX% ~

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Ehh, probability and statistics ain't my thing...so good luck

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Hm.. Are you sure that Q4 is correct?

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Bump.

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fixed, forgot to include a 0 in front of the decimal

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Yeah, now it works :)
But could you check Q7 too?

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This puzzle confirms something I have suspected for years. I hate math.

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ow mama.. math.. summer vacation.. no thanks, Thanks for your kindness though :D

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Question 6 confuses me. If the giveaway is fake is it deleted regardless? Also, do the mods only delete it if it is real?

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I have the same questions- also, will mods or the user delete first then?~

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are you sure Q7 is correct?

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^This. I think I got it but it doesn't accept..

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I've tried everything for this too.

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Same here. Got everything except this one, and I think I got my calculations right.

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Edit: fixed, sorry, for some reason I rounded to the nearest whole number >.<

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so I did ;p but it's after midnight and im drunk, so i may be understanding conditions wrong ;p

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thanks 3 instant solvers ; )

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4* ;p

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I think Q7 is still wrong.

EDIT: it is correct,my fault.

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If the giveaway is real , doesn't it all come down to the 90% thingy ?

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have problem with Q7, but it may be due to semantic problems with me not understanding english correctly ;p yet tried 3 examples of Conditional Probability based on 3 ways of understanding the question - all 3 incorrect :(

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My maths absolutely sucks, but I got Q1, hooray for me. I think I may give this one a skip :(

Edit: Although saying that, after some extensive amount of homework, only the last 2 questions remain. My brain is fried, I'll pick this up again tomorrow.

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I don't know if it is too late here, but I think your part with the 3 giveaways (q2 - q5) is completely wrong. Adding you to talk about the puzzle.

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it's not :>

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Well a lot of us have solved those so I don't think so...

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sorry. everything is fine. i just didnt see my error. too late here :)

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Damn math... Anyway, solved.

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Bump for solved :)

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Bump for solved.

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Oh, God, I shouldn't of thrown away all of my probability notes...

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I have to ask my math teacher for help

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forgot to bump this
solved

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Strange thing with the last two questions, already did my probability tree and still the answers aren't the correct ones :S

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you cannot do these solely on probability tree :>

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You can with Q6

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At work. Science calculator at home. Lazy. Coffee. Sandwich.

I'll get back to it in 8 hours, even if the giveaway is over by then.

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Casio...Casio never changes xD

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CASIO4LYFE NIGGA NONE OF THAT PLEB-TIER TI GARBAGE

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A math puzzle!? I've only seen one or two of those before, if only there were more logical puzzles around then I might actually spend time doing them :D

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Bump for solved

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Frustration is back! And im tired, maybe ill look at this tomorrow.

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Just a quick question about the bonus giveaway: would I need to solve the puzzle then comment in that giveaway for that particular puzzle to be eligible?

And would I still be able to do that, even though I'm only starting now?

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You need to comment in each giveaway you solved. Yes you can solve puzzles after theyre ended to be eligible for bonus giveaway.

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Ev11 has it correct.

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Hmm, how will you know he solved these puzzles if he didnt comment or enter? I knew sg works on magic!

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Oh derp, I had just woken up when I typed that post. I thought he was asking whether he had to solve puzzle #30

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Or maybe i didnt understand what he meant in the queston.

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No, you explained perfectly thanks.

Been struggling through some of these - I'm fairly new to SG so haven't seen all too many puzzles.

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Well, I got Q1. And after doing some reading, I got Q4. The rest requires some actual thinking, so I'm skipping this one.

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Closed 1 decade ago by jatan11t.

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