MHB Calculating Geometric Probability on a Round Table

Yankel
Messages
390
Reaction score
0
Hello all,

I have a question related to geometric probability. I think I solved it, but not sure, would appreciate your opinion.

We are given a round table with a radius of 50cm. At the center of this table there is another circle, with a radius of 10cm. A coin with a radius of 1cm is thrown on the table. Assuming that it landed on the table, what is the probability that the coin (the entire coin) is within the small circle ?

I said that the area of the big circle is

\[2500\pi\]

this is the sample space.

The set of the required event is the points creating the area of the small circle, but going 1cm inside, to allow the entire coin to be inside, so it is:

\[81\pi\]

Therefore the probability is:

\[\frac{81}{2500}\]

Am I correct ?

Thank you !
 
Mathematics news on Phys.org
I would be inclined to say:

$$P(x)=\frac{\pi\left(10-\dfrac{1}{2}\right)^2}{\pi\left(50-\dfrac{1}{2}\right)^2}=\left(\frac{19}{99}\right)^2$$
 
Not sure where Mark's $\dfrac12$ is coming from. The question says that the radius (not the diameter!) of the coin is 1cm. So I would give the answer as $\left(\dfrac9{49}\right)^2$. This assumes that the coin has to land so that it is entirely on the table. The OP's answer $\dfrac{81}{2500}$ assumes that it is allowed to land so that it precariously overlaps the edge of the table.
 
Yes, I misread radius as diameter...oops. :)
 
Insights auto threads is broken atm, so I'm manually creating these for new Insight articles. In Dirac’s Principles of Quantum Mechanics published in 1930 he introduced a “convenient notation” he referred to as a “delta function” which he treated as a continuum analog to the discrete Kronecker delta. The Kronecker delta is simply the indexed components of the identity operator in matrix algebra Source: https://www.physicsforums.com/insights/what-exactly-is-diracs-delta-function/ by...
Fermat's Last Theorem has long been one of the most famous mathematical problems, and is now one of the most famous theorems. It simply states that the equation $$ a^n+b^n=c^n $$ has no solutions with positive integers if ##n>2.## It was named after Pierre de Fermat (1607-1665). The problem itself stems from the book Arithmetica by Diophantus of Alexandria. It gained popularity because Fermat noted in his copy "Cubum autem in duos cubos, aut quadratoquadratum in duos quadratoquadratos, et...
I'm interested to know whether the equation $$1 = 2 - \frac{1}{2 - \frac{1}{2 - \cdots}}$$ is true or not. It can be shown easily that if the continued fraction converges, it cannot converge to anything else than 1. It seems that if the continued fraction converges, the convergence is very slow. The apparent slowness of the convergence makes it difficult to estimate the presence of true convergence numerically. At the moment I don't know whether this converges or not.
Back
Top