If humans originated in africa and migrated to other parts of the world, some time would be required for this to occur. at the modest rate of one kilometer per year, how many centuries would it take for humans originating in africa to travel to china, some 10,000 kilometers away?

1. there are 25 students who started computer programming in elementary school and 25 students who started computer programming in middle school. the first group had a mean final project grade of 95% and the second group had a mean final project grade of 92%. the line plot shows the differences after 10 rerandomizations. determine whether the difference in the means of the two groups is significant based on the line plot. explain your answer.

Acircle has a diameter will endpoints of (-2,8) and (6, 4). what is the center of the circle

7. if the value of x varies directly with the value of y, and x = 3 when y = 21. what is the valu y, and x = 3 when y = 21. what is the value of x when y = 105?