Answer
Geometric $r=2.5$
Work Step by Step
$4, 10, 25, 62.5, 156.25, 390.625, . . .$
$\frac{a_2}{a_1}=\frac{10}{4}=2.5=r$
$ra_2=25=a_3$
$ra_3=62.5=a_4$
$ra_4=156.25=a_5$
and so on. The sequence is geometric with common ratio $r=2.5$.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.