Probability question

I came across the following problem related to clinical trials. Within each family of a clinical trial, there are probability associated with individual indications within that family.

For instance,

Indications               Region                       POS

Indication1               US                      100%
                          Outside US             95%
Indication2              Worldwide              81%
Indication3              Worldwide              68%
Indication4              Worldwide              63%

I simulate scenarios by generating uniformly distributed random number in the interval [0,1]. If the random number is less than equal to 63%, all indications 1 through 4 become applicable. Similarly, when the number is less than equal to 81%, then only Indication 1 through 2 become applicable. So these are tiered probabilities such that Indication4 cannot be successful without the occurrence of indications 1,2, and 3.

What do these probabilities actually represent? Are these conditional probabilities? What would be the probability density function that would add to 1?

Thanks

#Combinatorics

Easy Math Editor

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Math	Appears as
Remember to wrap math in `\(` ... `\)` or `\[` ... `\]` to ensure proper formatting.
`2 \times 3`	$2 \times 3$
`2^{34}`	$2^{34}$
`a_{i-1}`	$a_{i-1}$
`\frac{2}{3}`	$\frac{2}{3}$
`\sqrt{2}`	$\sqrt{2}$
`\sum_{i=1}^3`	$\sum_{i=1}^3$
`\sin \theta`	$\sin \theta$
`\boxed{123}`	$\boxed{123}$