17. Find the mean and standard deviation for the population of sums of two dice. 18. Describe any differences in the mean and standard deviation above. 19. How does the difference in means show up in the graphs in 11 and 13? (Hint: think of the centers of each graph, since the graphs are symmetric). 20. How would the change in shape from 11 to 13 affect the standard deviation? (Hint: think about the graph as something you spread on food like butter or jelly. A higher standard deviation should be more spread, whereas a lower standard deviation should be more clumped). 21. How does the change in the min / max of each graph affect the standard deviation? (Hint: using the spread analogy again, think of the length of the x axis like the size of bread you're spreading over. The bigger the x axis, the bigger the bread, the larger the spread). 22. Based on your answers in 16-17 and your answers in 20-21, what had a bigger effect on your standard deviation? The change in the shape of the graph or the change in the x axis of the graph