Jane Street

Interview Question

Intern Interview
Jane Street

1) What is 12% of 47? 2) If I pick 2 cards from a shuffled deck (with no jokers), what is the probability that both are queens? 3) i) If I toss 4 fair coins and earn a dollar for every head, what is the expected value of this game? ii) If I can re-toss all 4 coins and must take the value from the second round, what is the expected value now? 4) How confident are you that you got 0, 1, 2, 3, or all questions correct, giving percentages? 5) If two teams play a best 4 out of 7 series, where each team has a 50% chance to win each round, what is the probability that the series lasts all 7 games?

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