When a scientist finds answers to questions brought up by scientific inquiry, he needs to:
A. immediately present his work to other scientists for their evaluation
B. be confident that he has found the right answers and stay with his conclusions
C. compare what he has found with other things that are known about the physical world
D. understand the consistency of the world and therefore know his answers are correct

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?