Violins are tuned GDAE (standard), violas are one octave lower, and I'm not sure but believe a Cello is one octave below
the viola.
The viola strings are CGDA. Notice that it is tuned in fifths, CdefGabcDefgA.
Counting the C, there are five notes to the next string.
Cello, viola, and violin are all tuned in fifths.
The bass is tuned in fourths. E-A-D-G.
Wierd, I just noticed that's a fiddle tuned backwards!
Fifths in one direction and fourths in the other!