Rotational Motion: Average angular acceleration of a CD

[adangerousdriver]

Homework Statement

"A compact disc (CD) stores music in a coded pattern of tiny pits 10−7m deep. The pits are arranged in a track that spirals outward toward the rim of the disc; the inner and outer radii of this spiral are 25.0 mm and 58.0 mm, respectively. As the disc spins inside a CD player, the track is scanned at a constant linear speed of 1.25 m/s."
"What is the average angular acceleration of a maximum-duration CD during its 74.0-min playing time? Take the direction of rotation of the disc to be positive."

r_inside=.025m
r_outside=.058m
v=1.25m/s
Calculated from previous parts of this problem:
ω_inside=50rad/s
ω_outside=21.6rad/s
t=74min=74*60s

Homework Equations

α=(ω_f-ω_i)/(Δt)

The Attempt at a Solution

I figured average angular acceleration would be calculated by subtracting the initial angular velocity from the final and dividing by the time interval, so I plugged in and performed this calculation:

(21.6rad/s-50rad/s)/(74*60s-0s)

to get -0.006 rad/s². This is online homework and it told me my answer is incorrect. I can't tell what I'm doing wrong. I've tried submitting both -0.006 and 0.006.

 

[gneill]

Your given values have 3 significant figures. What you've submitted only has one.

 

[adangerousdriver]

Your given values have 3 significant figures. What you've submitted only has one.

Welp that fixed it. Thank you!