Find Sn for the given geometric series. a1=0.15, a5=614.4, r=8

Question

anonymous · Answer

a.8370.51
b.546.15
c.70.75
d702.15
are the answer choices

amistre64 · Answer

Sn is notation for a partial sum ... but the options suggest that they want a particular nth partial sum.  you have provided no value for "n"

anonymous · Answer

it says to find Sn for the given geometric series. and i put up the problem

amistre64 · Answer

did you mistype the information then?  is r=8, spose to be "n=8"?

anonymous · Answer

its r

amistre64 · Answer

Sn, for a geometric series tells us how many successive terms they want us to add up.

S3 would tell us to add up the first 3 terms
S7 would tell us to add up the first 7 terms

S100 would tell us to add up the first 100 terms ... and so on

you have provided no value of "n" to determine how many terms they want you to actually add up.

anonymous · Answer

well idk thats what the problem says im confused also. well thanks ill just guess

amistre64 · Answer

if we had a specific value for n, we could use the formula:$$S_n=a_1\frac{1-r^n}{1-r}$$

anonymous · Answer

ok