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Mathematics 14 Online
OpenStudy (anonymous):

0

OpenStudy (anonymous):

Are you sure about that common ratio?

OpenStudy (anonymous):

yep

OpenStudy (anonymous):

Okay, so the ratio is greater than 1, which means the series diverges and there is no upper limit to the summation.

OpenStudy (anonymous):

so if it is divergent there is no infinite sum?

OpenStudy (anonymous):

Correct, a divergent series either increases without bound (approaches \(\infty\)) or oscillates between \(-\infty\) and \(\infty\).

OpenStudy (anonymous):

ok can u help with one more? @SithsAndGiggles

OpenStudy (anonymous):

sure

OpenStudy (anonymous):

The population of a type of local bass can be found using an infinite geometric series where a1 = 72 and the common ratio is \[\frac{ 1 }{ 4 }\]. Find the sum of this infinite series that will be the upper limit of this population.

OpenStudy (anonymous):

Alright, this is a convergent series so everything should work nicely. (Convergent because the common ratio is between -1 and 1.) \[\sum_{n=1}^\infty ar^{n-1}\] is the form of the series, and we're given that the first term \(a_1\) is 72. This means \[a_1=\sum_{n=1}^1 ar^{n-1}=ar^{1-1}=72~~\Rightarrow~~a=72\] and so the series is \[\sum_{n=1}^\infty 72\left(\frac{1}{4}\right)^{n-1}\] The sum of this kind of series is given by \[\frac{a}{1-r}\]

OpenStudy (anonymous):

is it 96?

OpenStudy (anonymous):

Yes

OpenStudy (anonymous):

thanks!! :)

OpenStudy (anonymous):

yw

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