Question 1119745
Here is a way to think about it: When the selection begins and all 9 astronauts are awaiting their assignment, how many are available to be selected for the first job? 9. After that 1 is selected, how many are available for the 2nd job? 9-1 = 8. How many for the 3rd job? 7. Answer: 9x8x7.
 Solve and you have your answer!