In a bag of keys, there are 12 silver keys, 5 black keys, 10 copper keys, and 3 painted keys of various colors. One key is drawn out at random. What is the probability that the key that is drawn is silver or copper?



Answer :

[tex]12+5+10+3=30[/tex] <-- the number of all keys
[tex]12+10=22[/tex] <-- the number of silver and copper keys

The probability is [tex]\frac{22}{30}=\frac{11}{15}[/tex]