View All num of num Add Photos DRW Trading This employer has taken extra steps to respond to reviews and provide job seekers with accurate company information, photos, and reviews. Interested for your company?Learn More. www.drwtrading.com Profile Unclaimed Overview Reviews Salaries Interviews Jobs Photos Benefits 28 Reviews 47 Salaries 50 Interviews Follow Add Review or Salary Follow Add Review or Salary Interview Question Trader Assistant Intern Interview Chicago, IL DRW Trading What is the chance that at least two people were born on the same day of the week if there are 3 people in the room? Tags: See more , See less 8 Answer Add Tags Answer Interview Answer 5 Answers ▲ 0 ▼ ~89.8% Anonymous on 22-Nov-2010 ▲ 0 ▼ incorrect.1-364/365*363/365 = 1-.9918 = .0082...something like this for 2 people, for 2+ add in the chance of 3 of 3.So first guy then gets 365/365 choices, next two get 1/365 Chase Schwalbach on 18-Jan-2011 ▲ 6 ▼ Also incorrect...They are asking if they were born the same day of the week not the exact same day as Chase alluded to.In this case the easiest way to do the problem is 1- probability that no one was born on the same day.1-(1)(6/7)(5/7)+ 19/49 or 38.78% traderguy on 22-Jan-2011 ▲ 2 ▼ My bad =19/49 trader guy on 22-Jan-2011 ▲ 4 ▼ Or you can calculate it directly:The chance of SELECTED two people(but not three) that are born on the same day is 1* 1/7 - 1/7*1/7 =6/49 Now we have 3 chooses 2 = 3 possible pairs, so the probability that any PAIR(but not all three) that are born on the same day is 3* 6/49 = 18/49. However, since the question asks "at least 2", we will need to add the possibility that all three are born at the same day, which is 1/7 * 1/7 = 1/49.So the final result is 18/49 + 1/49 = 19/49This obviously is a worse way of calculating it, but it's an alternative for some people who wants to think "straight". K Z on 26-Mar-2011 Add Answers or Comments To comment on this, Sign In or Sign Up.