[sa-is]

No, a standard bass guitar has 4 strings. There are exceptions such as the 5-string and 6-string basses, but a 3-string bass is not common. The extra strings on these exceptions typically extend the range of the instrument both lower and higher. There is also the “Sousaphonic” 3-string bass which is specially designed to be able to play the low pitches commonly found in the tuba (and other low-range brass instruments) that the 4-string bass cannot, but these are not as common or as well-known as the 4-string or 5-string variants.