Question

Hello! I am having trouble with these probability questions, please help me!
1. A standard cubical die is thrown. Calculate the probability that:
(a) the same number is thrown twice
(b) the two numbers thrown are different
2 A bag consists of 12 coloured balls. Five of the balls are red and the rest of blue. A ball is drawn at random from the bag. It is then replaced and a second ball is drawn. The colour of each ball is recorded.
(a) List the possible outcomes of this experiment (I did this no problem)
(b) Calculate the probability that:
(i) The first ball is blue
-to be continued-

Answer 1

-continuing-
(ii) The second ball is red
(iii) The first ball is blue and the second ball is red
(iv) The two balls are the same colour
(v) The two balls are a different colour
(vi) Neither ball is red
(vii) At least one ball is red

Answer 2

Sorry for so many questions, the only reason I am asking for help with so many is because I have tried them already and, well I got them all wrong

Answer 3

I have learnt about how to multiply probability together for independent events and add together for mutually exclusive ones but I am not sure what determines which method to use

Answer 4

Please post one question per thread

Answer 5

OK sorry, should I start a new one?

Answer 6

Yes that would be great

Answer 7

Ok

Answer 8

I agree with @ganeshie8 it's best to have one problem per post. Anyways, here is how to do part (a)
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1. A standard cubical die is thrown. Calculate the probability that:
(a) the same number is thrown twice
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There are 6 outcomes for any die roll since there are 6 sides (1,2,3,4,5,6)

If you roll say a 3, then there is a 1/6 chance that you'll roll a 3 again. Why 1/6? Because there are 6 outcomes possible and there's only one outcome we want, which is 3.

This can be generalized for any outcome (and not just 3)

So the answer to `1(a) ` is 1/6