In a student's music library on his mp3 player, the expected length of a randomly chosen song is 3.2 minutes.
a. Find an upper bound on the probability that a randomly chosen song is at least 5 minutes long.
b. If the standard deviation in the song lengths is known to be 0.8 minutes, find a bound on the probability that the song is between 2.9 and 3.5 minutes long.