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# Help with some worksheet questions watch

1. Hi, I've had some issues with these questions from some worksheets I've been given (don't worry they're not test questions or anything), and I was wondering if I could get some guidance with them. Would be much appreciated.

Attachment 723244723246

Just part b for both questions, any help would be appreciated, thanks in advance
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2. (Original post by thomoski2)
Hi, I've had some issues with these questions from some worksheets I've been given (don't worry they're not test questions or anything), and I was wondering if I could get some guidance with them. Would be much appreciated.

Just part b for both questions, any help would be appreciated, thanks in advance
Not sure what you need.

For the first one by the definition of the cdf,

For the second, each is the r.v. for 1 dice, and has a discrete uniform distrbution. The variance of which is a standard result.
3. Okay, I’m not sure how sure how to get P(X<=x). How would I go about that?
4. (Original post by thomoski2)
Okay, I’m not sure how sure how to get P(X<=x). How would I go about that?
If x=4 for example, it's just the value of F(x) when x=4, F(4) = 0.7
5. (Original post by ghostwalker)
If x=4 for example, it's just the value of F(x) when x=4, F(4) = 0.7
Ah, okay, I get it now. Thanks for the help
6. Working through it now, I'm also struggling with part a) of the first one, if you have any guidance on that?
7. (Original post by thomoski2)
Working through it now, I'm also struggling with part a) of the first one, if you have any guidance on that?
You're looking for the pmf, i.e. P(X=n) say, for the different values of n. Since the r.v can only take integer values, then

P(X=n) = P(n-1 < X <= n) = P(X<=n) - P(X<=n-1)= F(n) - F(n-1)

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