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and then modify it until it meets the conditions.
Alternatively, what standard distributions do you know that might provide an example, or be close enough to an example, that they can be modified to make them work for this case?
Can You Find ... Random Variable Edition
Age 16 to 18
Challenge Level 
You might find it useful to start with a specific example of a random variable, with its probability distribution written out explicitly, for example:
| $r$ | $1$ | $2$ | $3$ | $4$ |
| $\mathrm{P}(X=r)$ | $0.2$ | $0.3$ | $0.2$ | $0.3$ |
and then modify it until it meets the conditions.
Alternatively, what standard distributions do you know that might provide an example, or be close enough to an example, that they can be modified to make them work for this case?
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