Solve this equation for me

[leonid]

Re: Solve this equation for me

This is basically binary search >_>

Drop the glass ball from the 50th floor.. if it breaks, try to drop the ball from 25th, 13th, 7th, ...

If it doesn't break from 50th floor, try to drop it from 75th floor, etc

Maximum of ceil(log_2(100)) = 7 drops are needed

[MrRubix]

Re: Solve this equation for me

I did that while writing that post...

I don't know how to solve that problem you told us none of us will be able to figure out.. I tried the first part but I found myself having to solve a quintic polynomial inequality >_>

It is indeed a quintic polynomial inequality (but you're basically comparing a quintic to a cubic), but if done correctly, a lot of things will reduce nicely.

[Zipsnine]

Re: Solve this equation for me

You said that you answered that in an interview? So you were only able to use your head? No paper or pencil? In a certian amount of time?

[MrRubix]

Re: Solve this equation for me

This is basically binary search >_>

Drop the glass ball from the 50th floor.. if it breaks, try to drop the ball from 25th, 13th, 7th, ...

If it doesn't break from 50th floor, try to drop it from 75th floor, etc

Maximum of ceil(log_2(100)) = 7 drops are needed

what the **** lol if you could guarantee 7 drops, you would be God

So you drop from floor 50 -- it breaks. You try 25. It also breaks. You're out of spheres and you don't know the specific floor still -- binary search is a good place to start but since this approach does not work, it will hopefully give you a hint as to WHY it doesn't work and what kind of compensation is needed to offset its pitfalls.

[MrRubix]

Re: Solve this equation for me

You said that you answered that in an interview? So you were only able to use your head? No paper or pencil? In a certian amount of time?

Yeah, no paper and pencil -- it took me about 15 minutes to figure out. Got the job, though.

[GG_Guru]

Re: Solve this equation for me

Wait, why would they ask you that at a JOB INTERVIEW???

Unless you're like applying for cashier then that'd be understandable.

[leonid]

Re: Solve this equation for me

Oops, didn't see the part that I had only two glass balls >_>

brb, trying to solve again..

[MrRubix]

Re: Solve this equation for me

Wait, why would they ask you that at a JOB INTERVIEW???

Unless you're like applying for cashier then that'd be understandable.

Interviews for top trading firms and banks are extremely competitive -- you need to be very, very good with numbers. There's a reason why they pay so well, lol.

[GG_Guru]

Re: Solve this equation for me

Just show them your transcript and you're good to go.

Sounds sketchy but it works, people are suckers for high GPA. I can get work almost anywhere with my grades but then again that wouldn't be fair for all the other employers...

[leonid]

Re: Solve this equation for me

Transcript by only itself won't do the trick. I have GPA of 4.0 and still failed some interviews for summer internship..

[Zipsnine]

Re: Solve this equation for me

Hell if anyone can answer that in there head in about 15 minutes, should be able to work wherever the hell they want. Not really. But lets go with that for now

[GG_Guru]

Re: Solve this equation for me

You also need to be fluent and confident in the way you speak, the tone of your voice, and how you present yourself.

Leonid, it is possible. Just be cocky.

[MrRubix]

Re: Solve this equation for me

Another question given in an interview (a bit easier, also a favorite question of mine... simple and yet teaches a lot about expectation):

I have a game where you can roll a die and receive, in dollars, what you roll (rolling a 1 means you get $1, 2 you get $2, etc). However, assuming you are risk-neutral (e.g. equally sensitive to a gain of X versus a loss of X), and assuming there is a fee to play this game, what is the maximum fee you should be willing to pay to play this game?

What about with two dice? You roll the first one and can either accept it and get paid what you rolled, or you can discard it and take whatever you roll on the second die. How much would you be willing to pay for THIS game?

Three dice?

N dice?

[leonid]

Re: Solve this equation for me

@GG_Guru That's not how the interviews for technical jobs work

[MrRubix]

Re: Solve this equation for me

Just show them your transcript and you're good to go.

Sounds sketchy but it works, people are suckers for high GPA. I can get work almost anywhere with my grades but then again that wouldn't be fair for all the other employers...

Believe me, GPA is NOT enough at some places. Again, many firms are extremely, extremely competitive. Like, Goldman Sachs will probably not even look at your resume unless you're at least a 3.7 at an Ivy or a 4.0 at a non-Ivy, and even then you need to get their questions right and still have a smooth interview/discussion. People with 4.0's get rejected all the time.