The speed of the fan is 1884 inches per second.
Step-by-step explanation:
Revolution per minute= 4000
Radius = 4.5 inches
Circumference= 2π r
= 2(3.14) (4.5)
= 28.26 inches
1 revolution= 28.26 inches
4000 revolution= (28.26) (4000)
=113040 inches per minute
= 113040/60
= 1884 inches per second
The speed of the fan is 1884 inches per second.