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# A-Level Statistics 2 Continuous Random Variables Help Watch

1. Can someone please explain to me why the solution to question 3a as shown in the solution photo is true and why?
2. (Original post by BenRichi_)
Can someone please explain to me why the solution to question 3a as shown in the solution photo is true and why?
Do you understand what a cumulative distribution function is? The C.D.F tells you the probability i.e: it is the 'area' under your graph.

Since , this represents your total area which is and you know the total area under your graph has to be 1 since probabilities can never exceed 1. Hence the equation follows and you solve it to fine .

Edit: If you're having trouble understanding what a CDF is/does, this video may prove useful.
3. (Original post by Zacken)
Do you understand what a cumulative distribution function is? The C.D.F tells you the probability i.e: it is the 'area' under your graph.

Since , this represents your total area which is and you know the total area under your graph has to be 1 since probabilities can never exceed 1. Hence the equation follows and you solve it to fine .

Edit: If you're having trouble understanding what a CDF is/does, this video may prove useful.
Thank you for your response, I do understand what a c.d.f is and I understand that the area underneath it is 1 however I don't understand why
4. (Original post by BenRichi_)
Thank you for your response, I do understand what a c.d.f is and I understand that the area underneath it is 1 however I don't understand why
The piecewise function says that for and from this you can infer that , it's mainly 'cause the question is crappily written to be fair, they should have said ; so I understand your confusion.
5. (Original post by Zacken)
The piecewise function says that for and from this you can infer that , it's mainly 'cause the question is crappily written to be fair, they should have said ; so I understand your confusion.
Ah okay, thank you for the help it is much appreciated!
6. (Original post by BenRichi_)
Ah okay, thank you for the help it is much appreciated!
No worries.

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