abhisheknandy08
Q1.
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 sitnext to only one of the four other students from the group?
(A) 5%
(B) 10%
(C) 15%
(D) 20%
(E) 25%
Solution:If bob and Lisa have to sit next to only of the other 4 members of the group then Bob and Lisa must sit at the extremesBob and Lisa can sit at the extreme two positions in 2! ways
Remaining 3 persons can sit between bob and lisa in 3! ways
i.e. Total Favorable Seating arrangements = 2!*3! = 12
Total Possible Seating arrangements of 5 people = 5! = 120
Probability = 12/120 = 1/10 = 10%
Answer: Option B
abhisheknandy08
Q2.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 number of ways of seating if
both of them will sit next to only one other student from the group?
Thanks .
This language is confusing and lacks clarity however my interpretation worked like this
This Question means that Both must sit next to only one Common Student i.e. both Bob and Lisa are separated by just one seat between themSo consider the Pair of Bob and Lisa separated by one seat between them and this pair can move in 3! ways and bob and Lisa can exchange seats in 2! ways
i.e. Ways in which Bob and Lisa can sit = 3*2! = 6 ways
Remaining 3 persons can sit in 3! ways
i.e. Total Favorable Seating arrangements = 6*3! = 36
and Total Possible Seating arrangements of 5 people = 5! = 120
Probability = 36/120 = 3/10 = 30%