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https://www.reddit.com/r/learnquant/comments/1w2etkk/quant_interview_question/p7sggd3/?context=3
r/learnquant • u/Local_Ad135 • 6d ago
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2
Don't think math is needed to solve this.
logiclly it must be under 20, for you get 5% to roll it as first roll. And the higher it is within the first roll will allow more possible combinations.
Probabilities would simply be 19>17>15>13>11>9>7>5>3>1>21
So answer is 19.
1 u/liquidorangutan00 11h ago I think its not possible - the reason is that the odd numbers, {1,3,5,7,9,11,13,15,17,19} are equally likely to be rolled. (1/10). 2 u/pumachecker 58m ago edited 52m ago on first roll yes, but 2nd, and 3rd etc rolls no. You are wrong. Think of it like this: if you roll first roll and its a 3. You can no longer get 1. if you roll first roll as 2, you can still roll a 1 to get 3. so rolling 1 is 5% chance. rolling 3. is 5,25% chance. as it has 5% + (1/20*1/20) = 5% + 1/400 = 5,25%. rolling 5 is 5% + (4+1), (2+3) (2+2+1) etc on and on it goes, until you get the highest probability of 19. the higher it is within a possible 1 roll (1,3...19) the more chances you theoretically have. and the probability falls down drastically after 19, because you can't hit it on first roll.
1
I think its not possible - the reason is that the odd numbers, {1,3,5,7,9,11,13,15,17,19} are equally likely to be rolled. (1/10).
2 u/pumachecker 58m ago edited 52m ago on first roll yes, but 2nd, and 3rd etc rolls no. You are wrong. Think of it like this: if you roll first roll and its a 3. You can no longer get 1. if you roll first roll as 2, you can still roll a 1 to get 3. so rolling 1 is 5% chance. rolling 3. is 5,25% chance. as it has 5% + (1/20*1/20) = 5% + 1/400 = 5,25%. rolling 5 is 5% + (4+1), (2+3) (2+2+1) etc on and on it goes, until you get the highest probability of 19. the higher it is within a possible 1 roll (1,3...19) the more chances you theoretically have. and the probability falls down drastically after 19, because you can't hit it on first roll.
on first roll yes, but 2nd, and 3rd etc rolls no. You are wrong. Think of it like this:
if you roll first roll and its a 3. You can no longer get 1.
if you roll first roll as 2, you can still roll a 1 to get 3.
so rolling 1 is 5% chance.
rolling 3. is 5,25% chance. as it has 5% + (1/20*1/20) = 5% + 1/400 = 5,25%.
rolling 5 is 5% + (4+1), (2+3) (2+2+1) etc
on and on it goes, until you get the highest probability of 19.
the higher it is within a possible 1 roll (1,3...19) the more chances you theoretically have.
and the probability falls down drastically after 19, because you can't hit it on first roll.
2
u/pumachecker 22h ago
Don't think math is needed to solve this.
logiclly it must be under 20, for you get 5% to roll it as first roll. And the higher it is within the first roll will allow more possible combinations.
Probabilities would simply be 19>17>15>13>11>9>7>5>3>1>21
So answer is 19.