web2.0calc
 
+0  
 

 counting problem

0
439
5
avatar

4 girls and 8 boys are standing together. In how many ways can a 7- person committee be selected from the group if at least 2 girls must be included?

 Jul 25, 2020

5+0 Answers

 #1
avatar+118608 
0

NOTE: This answer is WRONG.

So it is an example of what will not work!

 

 

Take 2 girls first     4C2

then take 5 from what is left      10C5

 

then multiply the answers together.

 

That is assuming all committee members are equal.

 Jul 25, 2020
edited by Melody  Jul 25, 2020
edited by Melody  Jul 25, 2020
 #2
avatar
0

melody that is incorrect

Guest Jul 25, 2020
 #3
avatar+118608 
0

Ok, please justify your response (why do you think so?) 

Melody  Jul 25, 2020
 #4
avatar
+1

when you choose 2 girls then 5 other members you overcount (you can choose all 4 girls by choosing the first two, then choosing the other 2 girls and other 3 boys when you choose the other five, OR by choosing the last two girls first, then choosing the first two girls +other 3 boys)

Guest Jul 25, 2020
 #5
avatar+118608 
0

Yes thank you, I can see that your are correct, I have overcounted  blush

 

So I needed to looked at the 3 scenarios separately and then add the probablities together.

2 girls+5 boys

3 girls+ 4 boys

4 girls + 3 boy

Melody  Jul 25, 2020
edited by Melody  Jul 25, 2020

0 Online Users

Top Users

avatar+128408 CPhill moderator
avatar+118608 Melody moderator
avatar+33615 Alan moderator
avatar+14905 asinus moderator
avatar+9519 MaxWong
avatar+3144 admin administrator
avatar+2440 GingerAle
avatar+1763 tomtom
avatar+1484 bader
avatar+1037 parmen
avatar+1030 blackpanther

Sticky Topics