BERTIE (or anyone who really understands) Please can you help here:
Different (but realted ) Question:
I have six bottomless jars of lollies. They are Red, Green, blue, yellow, orange and black respecitvely.
I want to randomly choose 2 lollies. How many combintions are in the sameple space and what is the probability that one is red and one is green.
I am told it is appropriate to use the stars and bars method for a question like this
https://www.youtube.com/watch?v=5hF59P8tmQc
so there are (2+6-1)C2 possible combinations. 7C2 = 21
I just want one of those so the probability is 1/21
Now I want to toss 2 identical dice. and I want to know what is the probability of tossing a 2 and a 3
For a question like this it is normal to drawn a 6 by 6 grid. There are 36 possible outcomes but there are 2 ways that I can get a 2 and a 3. So the prob of throwing a 2 and a 3 is 2 /36 = 1/18
NOW why are these questions done differently.
6 colours all equally likely to be chosen I chose 2 of them
6 numbers all equally likely to be chosen I chose (roll) 2 of them.
To me the questions seem Identical but I am assued that they are not.
My question is WHY ARE THEY DIFFERENT ?????
Can anyone to try and explain this to me, I just don't get it.
I'd be very grateful if anyone could get the difference through to me.