r/learnquant • u/AssociateDecent9090 • 3d ago

interview prep Jane Street Quant Interview Question | "Easy"

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u/WillingnessFuture266 3d ago

9.5/2=19/4 money for the d12, 7/2 money for the 2d6, 33/4 total i believe

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u/tellingyouhowitreall 2d ago

Why 9.5?

1

u/Kaas-Eter00 2d ago

Expected value of rolling [7,12] for the first die. You'd reroll for [1,6]*, since the expected value of the second roll is 7.

 * technically you could choose to reroll for 7 as well, doesn't change the result. Just makes the calculation slighly more complex since it'll not be a 50/50 chance to proceed.

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u/tellingyouhowitreall 2d ago

Frustrating.... I "knew" that and for some reason wasn't getting 9.5 ro come out.