If S6=953.344 and r=35, what is the value of a1?

Answer 1

S6 = 953.344 r=35

It's a geometric series with common ratio = 35

a1 = Sn(1-r)/(1-r^n)

SN= a1(1-r^N)/(1-r) = a1(1-35^6)(1-35) =a1(-18382655635

a1 = 953.344(1-35)/(1-35^6) = 953.344(-34)/(-1838265624) = 32413.696/ 1838265624

=1.763275969 x 10^-5

=about 0.0176

=about 0.02

UNLESS the problem was really written to mean r = 3/5, not 35 (sometimes, for some reason the "/" gets left out and shows up as a space if at all)

then

953.344 = a1(1-(.6)^6)/(1-.6) = a1(.953344)/.4

a1 = .4(1000) = 400