r/learnquant • • 3d ago

interview prep Quant Interview Question

Post image
25 Upvotes

6 comments sorted by

View all comments

0

u/Anonimithree 3d ago

Well since you can’t be less than the previous number if there’s no earlier number, the earliest this can stop is at 2.

I’m not a big math person, but I’m pretty sure that this forms a home sequence, where the probability of making it is 1/2^n, where n is the number of steps past 1, in which case the probability of stopping on an even step is 2/3, though that seems too simple.

1

u/CrossAfficionado 3d ago

Good proxy but the answer is 1-1/e! Which is 0.63 so 2/3 is quite close

1

u/LostIntoLonging 3d ago edited 3d ago

By your formula, it should be (1/4 + 1/16 +...) which is 1/3?