Christina bought a yoyo from a company that claims that, with each retraction, the string rolls up by 70% of the original length. She sets up a tape measure and throws the yoyo 3 times. Her data are charted below.
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OpenStudy (katecc379):
OpenStudy (lord_box):
This is a geometric series.\[a_n = a_1*r ^{n-1}\]
OpenStudy (lord_box):
where a_1 is the initial term, 3, and r is the common ratio, 0.7.
OpenStudy (lord_box):
this is the formula for a sum of a geometric series:\[S_n = \frac{ a_1(1-r^n) }{ 1-r }\]
OpenStudy (faiqraees):
Use the formula
\[\large\rm Sum=\frac{initial(1-(\frac{rate}{100})^{times}) }{1-(\frac{rate}{100})}\]
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OpenStudy (katecc379):
what is r
OpenStudy (lord_box):
r is the rate, which is 0.7, since it becomes 70% shorter.
OpenStudy (katecc379):
then what is the times
OpenStudy (lord_box):
times is the number of throws.
OpenStudy (katecc379):
so 10?
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OpenStudy (lord_box):
yes
OpenStudy (katecc379):
that gave me 3.02 which isn't an option
OpenStudy (faiqraees):
initial is 3
Rate is 70/100
Times is 10
Try again using these values
OpenStudy (lord_box):
You divided the rate 0.7 by 100. 0.7 is already divided by 100.
OpenStudy (katecc379):
wait np 9.72?
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