Geometric sequence pre-calc
with questions highlighted in red

Yeap, number 6 is growing the fastest, because 1.189 is the largest of the growth factor, now that's just the growth factor, no the growth rate.

growth rate will be 1.189 - 1, or 0.189, in decimal format, let's put it in percentage format, 0.189 * 100, or 18.9%.

and yes, you're correct again, 3 is shrinking fastest, because 0.78 is the smallest growth factor, so its growth rate is

0.78 - 1, or -0.22, is a negative rate, so if we put in decay term is just 0.22 in decimal format, let's put it in percentage format

0.22 * 100, or 22%.