13 votes
Accepted

frog on a number line

It's easy to see by transforming the problem into a symmetric one - instead of a 1/3 vs. 2/3 jump to B or D, make a third branch so it's a uniform 1/3 chance of going to B, D, or D' (which in turn has ...
Nuclear Hoagie's user avatar
9 votes

frog on a number line

The answer is because note
Florian F's user avatar
  • 26.3k
8 votes

frog on a number line

Let's make every state in the game worth an amount of money to be in: A B C D E $6 $4 $2 $1 $0 With the way that the prices are ...
Misha Lavrov's user avatar
  • 1,395
7 votes

Was Humpty Dumpty right?

NOTE: Answer pre-dates correction to the question. Humpty Dumpty is now correct. Humpty Dumpty is wrong. Both twins tell the truth on Sunday, so neither of them could give that reply. Hence it is ...
Simon G.'s user avatar
  • 246
5 votes

frog on a number line

The transition probability matrix is $$ P = \begin{pmatrix} 1& 0& 0& 0& 0\\ 1/2& 0& 1/2& 0& 0\\ 0&...
RobPratt's user avatar
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4 votes
Accepted

Colliding Bullets again

I believe the exact answer you're looking for is Explanation: This appears to corroborate Dmitry's rather than dipodomys's simulation, even if Dmitry's is flawed in design. The conclusion is at ...
Feryll's user avatar
  • 2,172
3 votes

Was Humpty Dumpty right?

Humpty Dumpty is wrong. (well, depending on what assumptions you make interpreting the puzzle) Humpty's answer assumes that this is equally likely to have occurred on any given day regardless of the ...
sadvak's user avatar
  • 31
3 votes

Expected number of steps

Here are the first $10$ values, obtained via a Markov chain with $\binom{2N}{N}$ states, one for each placement of $N$ cars in $2N$ spots: \begin{matrix} N & \text{expected number} \\ \hline 1 &...
RobPratt's user avatar
  • 11.5k
2 votes

Colliding Bullets again

Update: fixed a mistake in my code where I didn't properly account for whether the trajectory of the bullets colliding was after the bullets were fired. I took a shot at this problem by coding up a ...
dipodomys's user avatar
  • 121
1 vote

frog on a number line

Let $p$ be the probability that a frog standing on C ultimately reaches A, as required. This probability $p$ will therefore apply both to a frog starting out its journey, and to a frog who has ...
mathswithronald's user avatar
1 vote

frog on a number line

This already has a solution but for the sake of variety, here's a numerical solution in Google Sheets (also applicable to Excel). A B C D E 1 0 0 0 0 1 =1/2 * A1 + 1/2 * C1 =1/3 * B1 + 2/3 * D1 =1/...
matt_rule's user avatar
  • 269
1 vote

frog on a number line

Consider the set $S$ of all paths from $C$ to $A$, where a path is represented by a concatenation of $B$, $C$, and $D$ ending with $A$. For instance, $BCDCBA$ represents the path $C->B->C->D-&...
Robearz's user avatar
  • 111
1 vote

Expected number of steps

Partial Answer - Simulation Welcome to this site @12HackingEarth. Those assumptions are made in the simulation (If I understood correctly your challenge): Any car can be selected, independently of ...
10010100102ohno's user avatar

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