Permutations (1 Viewer)

[flon]

In a train compartment, there are 8 seats, with 4 facing the front and 4 facing backwards.

a) if 5 people sit in the compartment, in how many ways can they be arranged?

b) if 2 of the people do not like sitting backwards, in how many ways can the 5 people be arranged.

c) Find the probability that 2 particular people will sit opposite each other if seating is arranged at random.

Thanks in advance

 

[lolman12567]

In a train compartment, there are 8 seats, with 4 facing the front and 4 facing backwards.

a) if 5 people sit in the compartment, in how many ways can they be arranged?

b) if 2 of the people do not like sitting backwards, in how many ways can the 5 people be arranged.

c) Find the probability that 2 particular people will sit opposite each other if seating is arranged at random.

Thanks in advance

hmm odd question, never done one like this. i'll give it a go

a) 8P5
b) 4P2 x 6P3
c) 4x6P3x2 / 8P5

really not sure

 

[lolokay]

yeah i'd say those answers are right

for c) you could also just say 1/7 straight away, since for a particular person, there are 7 remaining seats for the other paricular person to sit in -> so 1/7 that they choose the one opposite the person

 

[lolman12567]

thanks, your solution to c) is awsome.. i never saw that

 

[addikaye03]

Is that Q from Coroneas book? i'm pretty sure i've done it before.
Also, ftw, coroneas has an awesome probability section with some very hard Q, i suggest use it