Whether this ball will sink or float depends on which density is greater, the ball's or gasoline's. If the ball's density is greater, it will sink.
The density of the ball is its mass divided by its volume, i.e. 15.8/19.7 = approx. 0.829(g/cm^3).
The density of gasoline may vary, depending on many factors, but it generally lies between 0.7 and 0.78g/cm^3.
So the answer is: this ball will sink.