Question

What is the value of the fourth term in a geometric sequence for which a1 = 10 and r = 0.5 ?

Answer 1

   
$\bf\\ a_1 = 10~\text{\bf and} ~r=0.5\\\\ a_2 = a_1 \times r = 10 \times 0,5 = 5\\\\ a_3 = a_2\times r = 5 \times 0,5 = 2.5\\\\ a_4 = a_3\times r = 2.5 \times 0,5 = \boxed{\bf 1.25}$