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# S1 probability Watch

1. A discrete random variable X has the probability distribution (see pic attached)

E(X) = 0.95

1) Find the probability that X is greater than E(X)

2) Find a and b

Any help/tips? Cant really understand the first question! Many thanks
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2. (Original post by tjthedj)
A discrete random variable X has the probability distribution (see pic attached)

E(X) = 0.95

1) Find the probability that X is greater than E(X)

2) Find a and b

Any help/tips? Cant really understand the first question! Many thanks
For 1) What possibilities do you have for and what is the probability of each possibility occurring?

For 2) Recall that .
3. (Original post by joostan)
For 1) What possibilities do you have for and what is the probability of each possibility occurring?

For 2) Recall that .

oh right, so for the first one, i add the probability of x=1 x=2 and x=3 ?
4. (Original post by tjthedj)
oh right, so for the first one, i add the probability of x=1 x=2 and x=3 ?
Precisely.
5. (Original post by joostan)
Precisely.
thank you!
6. (Original post by tjthedj)
thank you!
No worries

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