Question 87312
Find the sum of the first 10 terms of the series: 6.4, 3.2, 1.6, ...
this is a geometric sequence. r is the common ratio between each number. {{{a[1]}}} is the 1st number of the sequence.
r=3.2/6=1/2
{{{S[n]=a[1]((1-r^n)/(1-r))=6.4*((1-(1/2)^10)/(1-1/2))=6.4*(1-(1/1024))/(1/2))}}}
{{{6.4*((1023/1024)*2)=13094.4/1024=12.7875}}}
Ed