It depends on the type of quartet. There are 4 instrumets in an instrumental quartet. If the term quartet is used to refer to the number of vocalists, then the number of instruments would be irrelevant.
It's called a Quartet. :D
A quartet.
nuno flores string quartet or corvonuno string quartet
The number in a quartet is four.
a quartet, i think
A group of four musicians or singers are called a quartet. A group of five musicians or singers are called a quintet.
It's called a Quartet. :D
mindless behavior which they is a quartet
Quartet or Foursome.
a little a lot of people live there
Millions upon millions of people
A quartet.
nuno flores string quartet or corvonuno string quartet
The number in a quartet is four.
Quartet
There are four instruments in a quartet.
There are four people in a quartet.