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"In each of the following questions, list a sample space consisting of equally likely outcomes and hence find the required probabilities"

1) There are 5 counters in a bag, each marked with a different number from the set {1,2,3,4,5} .Two counters are drawn from the bag,Find the probabaility the total score on the counters is

a) greater than 7

b) a prime number*

c) an odd number*

I made up a sample space diagram and i find out that out of 20 possible outcomes, 4 added up to be greater than 7. So my answer was 1/5

However i reread it and i done it through another way ... i said:

p(grater than 7) is the probabaility we get... p(3,5) + p(5,3) + p(4,5) + p(5,4)

(ok so this is essentially the same) BUT the probability of getting a 3 is 1/5 right? so we get (1/5 X 1/5) X 4 = 4/25

so ... which one i correct?

Please, please help!

Regrads

Mo

* i think ill attempt these again once i know the answer for this.