I am not following why the answer is 20. Can anyone advise on where I erred? My reasoning:
For any 10 events, we can expect 9 successes and 1 failure.
So to have a positive (or zero) expected value (i.e., the thief does not lose out), 9*x≥181.
Hence, x≥20.11… (repeating decimal).
So the minimum value must be greater than 20. Choosing 20 results in a slightly negative expected value. Have I missed something?
Thanks for your help!
You’re correct. What answer you choose depends on what the question wants from you, which is not really clear. For example, 23 could also be equally valid as the right answer.
What they meant could either be:
“approximately” as in choose the value closest to 181/9
they made a typo in the “BTW…” where they probably wanted to right “they do get…” bc of the “simply”
Anyway the problem isn’t posed that well, so you should only really focus on your methodologies — which is fine.
It’s “approximate” - 20 is much closer to the correct answer than 23.
