Negative Expected Value Bets Interview Questions
Negative expected value bets interview guide for recognizing losing propositions despite high win rates or tempting payouts.
Candidates learning to reject tempting but losing betting-style prompts.
Negative EV means the average loses
A negative expected value bet has an average net payoff below zero under the stated model. It can still win sometimes, but the weighted average is unfavorable.
High win rate can still lose
A bet that wins often can be negative EV if the losses are much larger than the wins or if the entry cost is too high.
Concrete example
If a bet wins 1 with 90 percent probability and loses 20 with 10 percent probability, expected value is 0.9 x 1 + 0.1 x -20 = -1.1.
Costs move bets negative
A fair-looking bet before fees can become negative after entry cost, spread, commission, or slippage in the toy setup.
Utility is a separate discussion
Someone might take a negative-EV gamble for entertainment or other utility, but that is outside a simple risk-neutral interview calculation unless the prompt asks for it.
Common mistakes
Candidates often overfocus on the probability of winning. Expected value requires payoff size, loss size, and costs as well.
Practice the pattern
Use the LeetQuidity curriculum and calibration to turn this topic into a focused practice plan.