There are no inaccurate items on the list you provided.
And what does 'the following" mean anyway ?
Urbfhdhehjrrr
Rrrrdndndndjdjdjdjjdjdjdjdkdmdmdmdkdjdjdjdjdid
a). Frequency = (4,000 rev/minute)·(1 minute/60 sec) = <em>66 and 2/3 rev/sec</em>
b). Period = 1 / frequency
Period = 1 / (66-2/3 rev/sec)
Period = 1/66-2/3 sec/rev
<em>Period = 0.015 sec/rev </em>