Chapter 11 - Section 11.2 - Arithmetic and Geometric Sequences - Exercise Set - Page 647: 65

multiple answers; see details below

With $a_1= \$11,782.40 $ and $r= 0.5 $, then, \begin{array}{l} a_2=a_1(r)\\ a_2=11,782.40(0.5)\\ a_2=\$5,891.20 ,\\\\ a_3=a_2(r)\\ a_3=5,891.20(0.5)\\ a_3=\$2,945.6 ,\\\\ a_4=a_3(r)\\ a_4=2,945.6(0.5)\\ a_4=\$1,472.80 .\end{array}