Could someone help me with this question ?(adsbygoogle = window.adsbygoogle || []).push({});

There are two locks on the door and the keys are among the six different ones you carry in your pocket. In a hurry you dropped one somewhere.

a) What is the probability that you can still open the door ?

b) What is the probability that the first two keys you you try will open the door ?

The answers are:

a)2/3

b)4!/6!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Question of counting and probability

**Physics Forums | Science Articles, Homework Help, Discussion**