Using geometric sequence concepts, it is found that:
a) The rule is: [tex]P_n = 750000(0.5)^{n-1}[/tex].
b) An exponential relationship exists between the two variables.
A geometric sequence is a sequence in which the result of the division of consecutive terms is always the same, called common ratio q.
The nth term of a geometric sequence is given by:
[tex]a_n = a_1q^{n-1}[/tex]
In which [tex]a_1[/tex] is the first term.
A geometric sequence represents an exponential relationship between the variables.
In this problem, considering that the first-place finisher wins half of $1.500.000 in total prize money, and each finisher earns half of the one who finished above, the first term and the common ratio are given by:
[tex]a_1 = 750000, q = 0.5[/tex].
Hence the nth term of the sequence is given by:
[tex]P_n = 750000(0.5)^{n-1}[/tex]
More can be learned about geometric sequence concepts at https://brainly.com/question/11847927
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