Question

How many ways are there to seat 4 people in a 9-passenger automobile? Assume that some times there will be no one in the driver's seat.

Answer 1

we have 4 person and 9 seat, first one can choose from 9 seats, second 8, third 7, fourth from 6,

so there are 9*8*7*6 ways


-wekku

Answer 2

so 3024 ways?

Answer 3

yes

Answer 4

I disagree.

Answer 5

why?

Answer 6

It would only be that many if we care who is sitting in which seat.

Answer 7

How many ways are there to seat 4 people in a 6-passenger automobile? Assume that some times there will be no one in the driver's seat.

what about this question? same type just different numbers

Answer 8

yeah. same type deal. I think you are being asked to do combinations again.

You have a pool of 9 seats. You will be picking 4 of the 9 seats to fill.

Answer 9

So how many different combinations of 4 seats can you make from 9 seats?

Answer 10

ummmm i'm not sure

Answer 11

Recall our previous notation?

Answer 12

How big is the pool?

Answer 13

6?

Answer 14

i'm talking about the six passenger car

Answer 15

Ok, and how many seats will we pick for the combinations?

Answer 16

4?

Answer 17

So the answer in nCr notation is?

Answer 18

30?

Answer 19

No, write the nCr notation first.

Answer 20

6!/4!(6!-6)!

Answer 21

Close!

Answer 22

\[\frac{6!}{4!(6-4)!}\]

Answer 23

ahhhhhh! i got it mixed up!

Answer 24

so 60?

Answer 25

Nope

Answer 26

\[\frac{6!}{4!(6-4)!} = \frac{6!}{4!2!} = \frac{6\times 5}{2!} = \frac{30}{2} = 15\]

Answer 27

so the answer is 15?

Answer 28

maybe. Did you check my work?

Answer 29

it should be 360

Answer 30

how so?