hw_lect1-1: 1 point; showing both graph and estimate width.

hw_lect2-1: 2 point; partial 0.5 for each example, no more point will be taken off after 2 point.   

hw_lect2-2: 1 point; showing the dataset and require graph. 

1.16: 1point; showing both graph (with log /without log).

hw_lect3-1: 2 point; partial 0.5 for each example.

hw_lect3-2; 1 point; plot out the histogram (should have exponential looking). 

1.11(b) 2 point: partial 1 point for graph, 1 point for relative frequency