(05.05 HC) The graph shows the distance, y in miles, of a moving train from a station for a certain period of time, x, in hours: What is the speed (in miles per hour) of the train?
A. 100 mile per hour
B. 50 miles per hour
C. 150 miles per hour
D. 400 miles per hour

Aclassroom is made up of 11 boys and 14 girls. the teacher has four main classroom responsibilities that she wants to hand out to four different students (one for each of the four students). if the teacher chooses 4 of the students at random, then what is the probability that the four students chosen to complete the responsibilities will be all boys?