Math Is Fun Forum

uzurpatorul

Member

Registered: 2009-06-25

Posts: 11

Flys

2 Problems:

1st:
You are visiting your girlfriend and she orders pizza. Your evil girlfriend has perfect eyesight and notices fly droppings in three places on the pizza. She is seeking revenge on you for refusing to babysit her poodle and proceeds to cut the pizza. Assuming that the droppings occurred independently and in random places, what is the probability (the solution format is x/y where gcd(x,y) = 1) that she will be able to cut a half-circle pizza slice with all three droppings in one half?

2nd:
A meatball has four fly droppings on it. These droppings, are in random places and you must calculate the probability (x/y format, gcd(x,y)=1) that you are able to cut a semi-sphere with all four droppings on one side.

Tigeree

Member

Registered: 2005-11-19

Posts: 13,883

Re: Flys

fly droppings? How does she know they're fly droppings?

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People don't notice whether it's winter or summer when they're happy.
~ Anton Chekhov
Cheer up, emo kid.

uzurpatorul

Member

Registered: 2009-06-25

Posts: 11

Re: Flys

She is allergic only to fly droppings, and she started having the allergic reaction. ;-)

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Flys

Has this anything to do with the ham-sandwich theorem?

Last edited by JaneFairfax (2009-07-11 05:55:34)

uzurpatorul

Member

Registered: 2009-06-25

Posts: 11

Re: Flys

Just in the sense that you have only one cut to get the half.(either half circle/or half meatball).

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: Flys

I'm pretty sure ham sandwich doesn't apply here. In each case there are too many droppings, and the aim isn't to cut them in half either.

The first question made me think of this one.
The second is a harder version that I *think* should be solvable using the same techniques.

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Why did the vector cross the road?
It wanted to be normal.

Tigeree

Member

Registered: 2005-11-19

Posts: 13,883

Re: Flys

How does she know that she is allergic to fly droppings, has she had them before? That doesn't seem as bad as I first thought it was, then. Now she has a reason to give her boyfriend all the fly droppings (a better reason, anyway).

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People don't notice whether it's winter or summer when they're happy.
~ Anton Chekhov
Cheer up, emo kid.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Flys

Hi uzurpatorul;

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Tigeree

Member

Registered: 2005-11-19

Posts: 13,883

Re: Flys

Yeah, that was obvious, I'm not good at fractions and I even knew that. I'm just curious about the fly droppings. How can you tell?

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People don't notice whether it's winter or summer when they're happy.
~ Anton Chekhov
Cheer up, emo kid.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Flys

Hi Tigeree;

Tell what?

Last edited by bobbym (2009-07-15 02:28:14)

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Tigeree

Member

Registered: 2005-11-19

Posts: 13,883

Re: Flys

Tell what fly droppings are, I've never seen any before.

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People don't notice whether it's winter or summer when they're happy.
~ Anton Chekhov
Cheer up, emo kid.

phrontister

Real Member

From: The Land of Tomorrow

Registered: 2009-07-12

Posts: 4,876

Re: Flys

Sorry, Tigeree, I couldn't find any pics...but I dug up some info for you:

According to Ebers Papyrus, which is "the oldest and arguably the most important preserved medical record of antiquity" (dating back to about 1552BC and apparently being "a complete record of known Egyptian medical knowledge"), the ancient Egyptian remedy for stopping a baby from crying was to give it a medicinal paste made from a mixture of spn seeds (whatever they are) and fly dung, which were strained and fed to the baby on four consecutive days. The crying was meant to cease instantly. (EB.782)

(I can think of a very good reason why the crying would cease instantly! And if I were that infant I'd make very sure I stopped crying before being fed that paste!)

According to a forensic source, fly droppings "are composed of a material homogeneous, amorphous, transparent, uncoloured, swollen, dissociated by, or dissolved in, water. They're "a yellow brown, some with a greenish reflection, others with a reddish reflection, faintly pronounced. They all strongly refract light, clear at the centre, dark on the periphery, as fatty bodies; also like fat granules, they're insoluble in water and in acetic acid and almost all dissolve in hot alcohol and in ether. Some small crystals in the form of short needles of undetermined chemical composition accompany them."

I'd avoid eating that pizza and the meatballs at all costs, the favourable weight of probabilities notwithstanding!

Last edited by phrontister (2009-07-15 21:08:49)

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"The good news about computers is that they do what you tell them to do. The bad news is that they do what you tell them to do." - Ted Nelson

Tigeree

Member

Registered: 2005-11-19

Posts: 13,883

Re: Flys

Wow, thanx for the info, phrontister! Now I see why that girl is allergic!

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People don't notice whether it's winter or summer when they're happy.
~ Anton Chekhov
Cheer up, emo kid.