13. In how many ways can 7 people be seated around a circular table if two of them
insist on sitting beside each other?
A 360 B 720
C. 1440
D. 5040
14. A box contain 8 red balls, 6 yellow balls, and 5 green balls. In how many ways
can we select 3 balls such that two are red and one is yellow?
A 56
B. 128
C. 168 D. 240
15. A box contains 7 red balls, 5 yellow balls, and 3 green balls. In how many ways
can we select 3 balls such that exactly 2 are yellow?
A. 100
B. 128
C. 240 D 256​