add lab-p13 and p13

lab-p13/README.md

lab-p13/images/README.md

lab-p13/images/bar_plot.jpg

lab-p13/images/horizontal_bar_plot.jpg

lab-p13/images/pie_plot.jpg

lab-p13/images/regression_line_plot.jpg

lab-p13/images/scatter_plot.jpg

lab-p13/lab-p13.ipynb

p13/README.md

p13/expected_dfs.html

p13/images/README.md

p13/images/add_group_member.png

p13/images/gradescope.png

p13/images/q10.jpg

p13/images/q16.jpg

p13/images/q17.jpg

p13/images/q18.jpg

p13/images/q20.jpg

p13/images/q5.jpg

p13/images/q6.jpg