Physics HELP NO CLUE?

Question

1. A figure skater begins spinning counterclockwise at an angular speed of 4.0 "PIE" rad/s. During a 3.0 s interval, she slowly pulls her arms inward and finally spins at 8.0 "PIE" rad/s. What is her average angular acceleration during
this time interval?
2. What angular acceleration is necessary to increase the angular speed of a fan blade from 8.5 rad/s to 15.4 rad/s in 5.2 s?

Answer 1

The average angular acceleration is simply the change in angular speed, divided by the time it takes to do so.

1.
Let A be the average angular acceleration:
A = (8*π rad/s - 4*π rad/s) / (3 s)
A = (4*π rad/s) / (3 s)
A = 4.19 rad/s^2

2.
A = (15.4 rad/s - 8.5 rad/s) / (5.2 s)
A = (6.9 rad/s) / (5.2 s)
A = 1.33 rad/s^2