• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

Permutations (1 Viewer)

blackops23

Member
Joined
Dec 15, 2010
Messages
428
Gender
Male
HSC
2011
There are 4 identical red marbles, 3 identical yellow marbles and 2 identical green marbles arranged in a row.

(i) How many different arrangements of just 5 marbles are possible if all 3 colours must be included?

Can someone please explain how to do this with copious amounts of detail lol?

So far I've got:

3R 1Y 1G
2R 1Y 2G
2R 2Y 1G
1R 1Y 3G
1R 3Y 1G
1R 2Y 2G

^these are the ways you can do the selection. But now what do you do?

Thanks appreciate the help
 

MATHSCAPE

Member
Joined
Apr 21, 2009
Messages
157
Gender
Male
HSC
2011
There are 4 identical red marbles, 3 identical yellow marbles and 2 identical green marbles arranged in a row.

(i) How many different arrangements of just 5 marbles are possible if all 3 colours must be included?

Can someone please explain how to do this with copious amounts of detail lol?

So far I've got:

3R 1Y 1G
2R 1Y 2G
2R 2Y 1G
1R 1Y 3G
1R 3Y 1G
1R 2Y 2G

^these are the ways you can do the selection. But now what do you do?

Thanks appreciate the help
can't have that.

what's the answer btw?
 
Last edited:

math man

Member
Joined
Sep 19, 2009
Messages
503
Location
Sydney
Gender
Male
HSC
N/A
There are 4 identical red marbles, 3 identical yellow marbles and 2 identical green marbles arranged in a row.

(i) How many different arrangements of just 5 marbles are possible if all 3 colours must be included?

Can someone please explain how to do this with copious amounts of detail lol?

So far I've got:

3R 1Y 1G
2R 1Y 2G
2R 2Y 1G
1R 1Y 3G
1R 3Y 1G
1R 2Y 2G

^these are the ways you can do the selection. But now what do you do?

Thanks appreciate the help
well with these possibilities...you work out how many ways you can have each:

3R 1Y 1G can be arranged in: ways to count for the repetition of the 3 R's.

2R 1Y 2G can be arranged in: ways to count for the repetition of the 2R's and G's

Now you repeat this for every situation you can have then add each as these are 'or' cases.
 

MATHSCAPE

Member
Joined
Apr 21, 2009
Messages
157
Gender
Male
HSC
2011
you've got all the different combinations, just do what math man said and you should get it.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top