The ball rolled for 13.2 s
Speed is scalar and no direction
[tex]\tt avg~speed=\dfrac{total~distance}{elapsed~time}=\dfrac{\Delta x}{\Delta t}[/tex]
A bowling ball rolls 33 m, with average speed = 2.5 m/s
So elapsed time :
[tex]\tt t=\dfrac{33~m}{2.5`m/s}=13.2~s[/tex]