perm question (1 Viewer)

[smallcattle]

how many ways can six girls and two boys be arranged in a row if there are atleast three girls seperating thr boys??

 

[smallcattle]

i have no idea how to do these questions

is there any techniques to interpret the questions?? i understand the basic ideas of perm and comb, but when applying to the questions, i just go totally lost

 

[Archman]

so u have: (some girls), [boy, girl, girl, girl], (maybe more girls), [boy], (more girls)
now in those three round brackets, we hafta distribute 3 girls, the number of ways doing this is the same as putting the two square brackets between the 3 girls. so 3 girls + 2 square brackets = 5 things, 2 of which are brackets. so there are 5C2 = 10 ways of doing so. now amongst the girls there are 6! ways of arranging themselves, while within the boys there are 2! ways
so its 10 * 720 * 2 = 14400 ways

 

[smallcattle]

ok.. i get that one now, but what about other questions..

is there a general rule to interpret questions??

 

[withoutaface]

ok.. i get that one now, but what about other questions..

is there a general rule to interpret questions??

If an event has two possibilities, and this event occurs y amount of times, and the question asks you to find the probability that one of the two possibilities occurs x times out of y, this is binomial probability. Learn to identify it, because it makes many questions ten times easier.
Basically you just have to work through papers and look at the questions and work out which questions warrant which approach, but binomial probability seems to be one of the types that lots of people have trouble identifying.

 

[cj_bridle]

yeh and if theres a probability question after a binomial check for binomial probability first.. 9 times out of 10 they put it after the binomial for a reason..

 

[mojako]

how many ways can six girls and two boys be arranged in a row if there are atleast three girls seperating thr boys??

I wonder why the boys must be separated by the girls..
In invisible text: just one of my pointless posts

 

[withoutaface]

I wonder why the boys must be separated by the girls.. ;
In invisible text: just one of my pointless posts

Because lesbians are more fun

 

[Archman]

especially when they come in threesomes

EDIT: sorry, bad pun unintended

 

[CrashOveride]

You put up the "EDIT", yet there is no message to tell us this had occured.
Hence, the pun was intended.

 

[Archman]

well if you edit your post right after your posted, either within a certain time frame or before someone else reads it (not sure which one). then the bit about u editing it won't show up.

 

[mojako]

and I think this only happens recently
(before it always showed Last edited on...)

 

[CrashOveride]

If that is so, my apologies.

 

[Constip8edSkunk]

no it has always been like that... if you edit within 2 minutes then you wont get the italic thing

 

[jumb]

no it has always been like that... if you edit within 2 minutes then you wont get the italic thing

Just insert it yourself!

Edit, scrap that, the information goes under your sig


This post was not ever edited... at all, actually it was once