Not an MCAT question, but its been bugging me.

[deleted74029]

---

Members do not see this ad.

If you haven't seen the movie 21 here is the problem: (sorry for any grammar mistakes I copied and pasted from another site)

You are on a game show and there are 3 doors and behind 2 doors there are goats and behind the other is a car (the game show host knows which door the car is behind). lets say you pick door A has the car initially and the game show host opens door C which reveals a goat (now only doors A and B remain). the game show host asks if you want to change your selection from door A to door B. this is were i get confused. apparently if you change your selection from door A to door B the chance of winning the car changes from the initial 33% to 67%. however, i dont understand why it wouldnt go to 50% instead of 67%.

 

[CYH]

Assuming you always choose to switch doors:

If you originally chose the wrong door, after switching you'll have the right one. (You have a 66.7% chance of choosing the wrong door initially)

If you originally chose the right door, after switching you'll have the wrong one. (33% chance of choosing the right door initially)

 

[onb2014]

It is because your chance of getting it right the first time is 1/3. Whether or not you select the right door, they always can open an incorrect door. Just consider the scenario that the prize is in A. If you pick A, then they'll open either B or C, and if you switch you're wrong. If you pick B, then they must open C, and if you switch to A, you'll be right. If you pick C, then they must open B, and if you switch to A, you'll be right. In 2 of 3 scenarios, switching will lead you to the right answer, in 1 of 3 scenarios, you switch to the wrong answer.

 

[Charles English]

the monty hall problem. classic.

http://en.wikipedia.org/wiki/Monty_Hall_problem


normally i don't offer up some wiki references, but this has diagrams...so have at it. tell you the truth though, i did have a pickle wrapping this one around my head at first too.

 

[engineeredout]

21 emphasizes why I did a math major. Math majors always get the hot girls and money and full rides to harvard medical school.

 

[deleted74029]

21 emphasizes why I did a math major. Math majors always get the hot girls and money and full rides to harvard medical school.

Haha of course, although I wondered why the movie left out the idea of loans. Like every student that goes to med school pays for it out of pocket. But I guess that wouldn't be interesting huh.

 

[deleted74029]

Oh and thanks for the explanations I understand it now. I guess that best way to simplify it is just assume that you probably picked the wrong door(66%), so its probably one of the others. Since now you know its not door 3. It "has" to be door 2.

 

[engineeredout]

Haha of course, although I wondered why the movie left out the idea of loans. Like every student that goes to med school pays for it out of pocket. But I guess that wouldn't be interesting huh.

There would be no plot whatsoever if he could just go to the bank and take out a loan.