prep1中的几道PS数学？？？

1.At a dinner party, 5 people are to be seated around a circular table.  Two seating arrangements are considered different only when the positions of the people are different relative to each other.  What is the total number of different possible seating arrangements for the group?

(A) 5

(B) 10

(C) 24

(D) 32

(E) 120

2.A company has two types of machines, type R and type S.  Operating at a constant rate, a machine of type R does a certain job in 36 hours and a machine of type S does the same job in 18 hours.  If the company used the same number of each type of machine to do the job in 2 hours, how many machines of type R were used?

(A) 3

(B) 4

(C) 6

(D) 9

(E) 12