iphone sales from the 2nd quarter in 2007 through the 2nd quarter in 2008 can be approximated by S(t) = -390t + 3,300t - 4,800 thousand phones (2 s t s 6) in quarter t. (t = 1 represents the start of the first quarter of 2007.)+ iPhone sales (thousands) 2,000 1,500 1,000 500 0 2 3 5 2007 Q2 2008 Q2 (a) Compute S'(t). S'(t) = How fast were the iphone sales changing in the first quarter of 2008 (t = 5)? (Be careful to give correct units of measurement.) S'(5) = thousand phones per quarter (b) According to the model, iphone sales did which of the following? O decreased at a faster and faster rate during 2007 (the interval [2, 4]) increased at a slower and slower rate during 2007 (the interval [2, 4]). O decreased at a slower and slower rate during 2007 (the interval [2, 4]) increased at a faster and faster rate during 2007 (the interval [2, 4])