Complexity Analysis - General Questions

If an O(n²) algorithm takes 1 second for n = 1000, about how long for n = 3000?

Which grows fastest as n increases?

The naive recursive Fibonacci function runs in:

What is the output of the following code?

count = 0
n = 16
i = n
while i > 1:
    i //= 2
    count += 1
print(count)

What is the output of the following code?

count = 0
n = 5
for i in range(n):
    for j in range(i):
        count += 1
print(count)