A group of 5 students bought movie tickets in one row next to each other. If Bob and Lisa are in this group, what is the probability that Bob and Lisa will each sit next to only one of the four other students from the group?
Answers
A) 5%
B) 10%
C) 15%
D) 20%
E) 25%
Bob and Lisa are students too. Given the above conditions, there are 2 possible seating arrangments:   scenario 1: LXXXB or   scenario 2: BXXXL   there are 5(4)3(2)1 = 120 total seating arrangements. in scenario 1, bob must be seated on the far right and lisa on the far left. this leaves 6 different possible seating arrangements among the other 3 students: 3(2)1 = 6. 6/120 = 1/20.   the prob of scenario 2 happening is also 1/20. either scenario 1 or 2 will occur so we sum the probs of 1 or 2 happening, 1/20 + 1/20 + 2/20 = 1/10 = .10.   answer is 10%.
<result>B</result>
A group of 5 students bought movie tickets in one row next to each other. If Bob and Lisa are in this group, what is the probability that Bob and Lisa will each sit next to only one of the four other students from the group?