Wiktionary
dope out
vb. (context transitive English) to figure out, to find out, find, decipher
Usage examples of "dope out".
It don't take a mastermind to dope out it was them two who did it.
They never did catch me using my spy-ray - it's on an awfully narrow beam, you know, and uses almost no power at all - so I've been able to dope out quite a lot of stuff.
This may be all, but it may not be-not by eleven thousand light-years -and I'm trying to dope out what is going to happen next.