+0  
 
+1
77
16
avatar+493 

 

is it 46?

 Jun 10, 2021

Best Answer 

 #9
avatar+2116 
+2

This has a really nice method. 

B will be left of A 50% of the time, right of A 50% of the time. 

5*4*3*2*1 total ways to be in a line, 50% of which are where B is on the left of A. 

5*4*3*2*1/2 = 60

 

=^._.^=

 Jun 10, 2021
 #1
avatar+199 
+1

oops lemme recalculate

 Jun 10, 2021
edited by mathisopandcool  Jun 10, 2021
 #3
avatar+199 
+1

30 ways i can explain it but my working got deleted when i was writing it

mathisopandcool  Jun 10, 2021
 #2
avatar+493 
+1

sure!

 Jun 10, 2021
 #4
avatar+199 
0

If B is adjacent to A we can make them as 1 letter, so  4!=24

 

If B is one away from A, we have 4 cases.

BCAD

BDAC

DBCA

CBDA

If B is two away from A we get:

BCDA

BDCA

24+4+2=30

30 ways

 Jun 10, 2021
 #5
avatar+199 
0

wait sorry its wrong im dumb

mathisopandcool  Jun 10, 2021
 #6
avatar+199 
0

there are 5 numbers not 4

 Jun 10, 2021
 #7
avatar+199 
0

You get 24

plus 

9

plus

12

plus

6

24+9+12+6

33+18

51 im rlly bad at math idk if this is r

mathisopandcool  Jun 10, 2021
 #8
avatar+114044 
0

How about you show your working mworkhard.

 Jun 10, 2021
 #9
avatar+2116 
+2
Best Answer

This has a really nice method. 

B will be left of A 50% of the time, right of A 50% of the time. 

5*4*3*2*1 total ways to be in a line, 50% of which are where B is on the left of A. 

5*4*3*2*1/2 = 60

 

=^._.^=

catmg Jun 10, 2021
 #10
avatar+114044 
+1

That is a REALLY nice method catmg.  Thanks for showing it :)

Give yourself a point!  

Melody  Jun 10, 2021
edited by Melody  Jun 10, 2021
 #12
avatar+2116 
+1

Thank you. :))

 

=^._.^=

catmg  Jun 10, 2021
 #11
avatar+114044 
+2

Lets have a look at your method mathisopandcool

 

XXXXB       4!             = 24

XXXBX       3*3!          =18

XXBXX       3*2! *2      =12

XBXXX      3!              =6

 

total = 24+18+12+6 = 60 ways

 

If you want me to explain any of these just ask.    cool

 Jun 10, 2021
 #13
avatar+33564 
+3

A  X  X  X  X       Four ways for B to be to the right

X A X X X           Three ways

X X A X X            Two ways

X X X A X              One way     total of 10 ways     

                                      the other three slots can be filled in   3 * 2 *1   ways  = 6 ways for EACH of the 10 possibles

      10 * 6 = 60 ways

 Jun 10, 2021
 #14
avatar+114044 
+1

That is a nice easy way too EP Thanks for showing us.

Your way is better than doing them all individually like in my demo. 

 

Personally, I like catmgs way best but it is really good to see lots of alternative methods.

Melody  Jun 11, 2021
 #15
avatar+33564 
+2

Agee!   catmg method  was pretty slick !   cool

ElectricPavlov  Jun 11, 2021
 #16
avatar+493 
+1

ok ok thanks for all the help!

 Jun 11, 2021

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