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# Gcse maths exam tomorrow - help! Watch

1. Ok, I really really need help on this question, because I always do not know how to complete these:

Nicholas has 30 beads in a bag.
9 are white.
8 are green.
13 are blue.

Nicholas takes two beads from the bag at random.
What is the probability that the two beads will NOT be the same colour??

I'm completely clueless on this one, can someone please show me the working out step by step and explain why each step happens?

Thankyou =)
2. (Original post by Instincts_2012)
Ok, I really really need help on this question, because I always do not know how to complete these:

Nicholas has 30 beads in a bag.
9 are white.
8 are green.
13 are blue.

Nicholas takes two beads from the bag at random.
What is the probability that the two beads will NOT be the same colour??

I'm completely clueless on this one, can someone please show me the working out step by step and explain why each step happens?
It's hard to describe, your best bet is to draw a tree diagram with the probabilities on them, work out all branches combinations which have different colours on them, then add them together
3. (Original post by Serano)
It's hard to describe, your best bet is to draw a tree diagram with the probabilities on them, work out all branches combinations which have different colours on them, then add them together
Wouldn't the total amount of combinations be well over 400?
4. (Original post by Instincts_2012)
Wouldn't the total amount of combinations be well over 400?
No there's 3 principal branches then 3 sub branches on each principle branch

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