I believe you ask about speed at the end of the hose:
The volume of the bucket is 225 liters which is equal to 225 \(dm^{3}\).
\(V=225dm^{3}\)
Hose's cross section can be counted with the typical circle's area formula (with diameter instead of radius, that's why you've got a fraction):
\(A=3,14*\frac{d^{2}}{4}}=0,19625dm^{2}\)
\(225dm^{3}\) are filled within 15 second.
As the bucket is being filled you can say that it's volume is the volume of the water that flowed out of the hose, then:
\(V=A*h\)
The speed of the water can be counted with equation:
\(v=\frac{h}{t}\)
After extracting h from the volume's equation you get:
\(v=\frac{V}{A*t}\)
When you count the fraction you get the answer:
\(v=76,43\frac{dm}{s}=0,7643\frac{m}{s}\)