Question

Help please???
Find S12 for the series 1 + 1.5 + 2.25 + 3.375 +...

Answer 1

r=1.5/1=1.5=3/2\[sn=\frac{ a(r^n-1) }{ r-1 }\]
n=12
calculate

Answer 2

is it 257.5?

Answer 3

@surjithayer

Answer 4

\[1\frac{ \left( \frac{ 3 }{ 2 } \right)^{12}-1 }{ \frac{ 3 }{ 2 }-1 }\]
\[=\frac{ \frac{ 531441 }{ 4096 }-1 }{ \frac{ 1 }{ 2 } }=2\left( \frac{ 531441-4096 }{4096 } \right)\]
\[=\frac{ 527345 }{ 2048 }=257.49 \]
so you are absolutely correct.