Question 8:
Your choice is correct: two figures are similar if all correspondant sides are in the same ratio.
In your case, the figure on the right have correspondant sides which are all three times the figure on the left, since

So, the two figures are similar and their ratio is 1:3.
Question 9:
We follow exactly the same approach: let's see if the radii and the heights are in the same ratio: the radii are in ratio

While the heights are in ratio

So, the answer is again yes, they are similar, and the ratio is 1.6.