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

.

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):


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:

The speed of the water can be counted with equation:

After extracting h from the volume's equation you get:

When you count the fraction you get the answer:
The other two bulbs stay lit with the same brightness.
Formula for acceleration: A=Force/Mass
A=F/M
A=80N/4.5kg
A=17.7 m/s^2
Unit for A is meters per second (m/s^2)
Hope this helps :)
Birth rate 10/1000 = +population
Death rate 9/1000 = -population
Immigration rate 3/1000 = +population
Emigration rate 7/1000 = -population
10/1000 - 9/1000 + 3/1000 - 7/1000= -3/1000
Growth rate = (-3/1000)(100%)= -0.3%
I would go with b because the seasons are caused by the tilt of Earth axis, not greenhouse gases