20 cm is the answer good luck
I know this is late and you probably got the answer but just in case its C. 5. :P
Answer:

Step-by-step explanation:
we know that
1 mile=63,360 inches
step 1
Find the circumference of the wheels

we have
-----> the radius is half the diameter
substitute


assume


Remember that
The circumference of the wheels represent one revolution
Convert 59 miles per hour to inches per minute

using proportion find the number of revolutions

therefore
substitute

Answer:
Therefore the rate change of height is
m/s.
Step-by-step explanation:
Given that a vertical cylinder is leaking water at rate of 4 m³/s.
It means the rate change of volume is 4 m³/s.

The radius of the cylinder remains constant with respect to time, but the height of the water label changes with respect to time.
The height of the cylinder be h(say).
The volume of a cylinder is 


Differentiating with respect to t.

Putting the value 



The rate change of height does not depend on the height.
Therefore the rate change of height is
m/s.