Could you pass this interview? The famous batteries and flashlight logic puzzle

MindYourDecisions

This is a famous problem that has been used in technical interviews, and it has even appeared on a Mathematical Olympiad. There are 4 good batteries and 4 bad batteries, and you need to insert 2 good batteries to make a flashlight work. How many tests do you need? 0:00 problem 1:53 estimate 5:18 s