I applied online. The process took 7 weeks. I interviewed at Jane Street (New York, NY) in Feb 2017
Interview
I applied online for a research intern. However, I was transferred to trader intern. The HR contacts me through email to arrange a phone interview. I got to the second round phone interview. The problems are about probability.
Interview questions [1]
Question 1
Suppose two players are playing a game. The first player chose an integer between 1-30. The second player picks a different one. After that, a random integer (x) between 1-30 will be generated. The player whose number is closer to x get paid x dollars.
Q: Would you go first or second? What number should you pick?
I applied online. I interviewed at Jane Street in Dec 2019
Interview
Had 3 phone interviews and then got invited to onsite where we did mock trading games based on probability questions. First two phone interviews were 30 minutes while the third was 60 minutes.
Interview questions [1]
Question 1
If A beats B in a race 60% of the time and B beats C 60% of the time, what percentage of the time does A beat C?
The process took 1 day. I interviewed at Jane Street in Feb 2012
Interview
It was a 30 minute 1 on 1 interview with an alum from my university. He asked me a few resume/background questions that he was clearly not very interested in and then we spent about 25 minutes of the 30 minute interview on generally basic mental math/probability questions. True to Jane Street form, the interviewer was wearing a t-shirt and chinos, and it seemed like he would not have cared at all about what I was wearing (i.e., not a suit). He also seemed to be making the questions up on the spot off the top of his head.
Interview questions [1]
Question 1
A bad king has 1000 bottles of wine. A neighboring king plots to kill the bad king, and sends a servant to poison the wine. the servant is able to poison only one of them before he is caught. The guards don't know which bottle was poisoned, but they do know that the poison is so potent that even if it was diluted 1,000,000 times, it would still be fatal. Furthermore, the effects of the poison take one month to surface. The king decides he will get some of his prisoners in his vast dungeons to drink the wine. At a minimum how many servants does he need to kill to find out the poisioned bottle of wine and will still be able to drink the rest of the wine in 5 weeks time?