Question

Can someone (preferably one of the long-term tutors) check my answers:

Researchers trap 23 devils, and find that 18 of them are infected. Provide an estimate of disease prevalence.

p-hat = (18/23)=0.783

Part II: assuming the same disease prevalence from above.
If they trap 2 devils, what’s the probability that they will get an appropriate pair (i.e. one uninfected female and one uninfected male)?

I used Combinatorics:
23 total, 18 infected and 5 uninfected
Prevalence: 0.783
5C2/23C2 = 10/253 = 0.0395
(0.0395)(.783) = .0309 or 3.1%

Just need to make sure I'm on the right track. Thanks for your help.

Answer 1

Forgot to add that the sex ratio is even and both have the same prevalence.