How do you change 0.000009074785 to 4 significant figures?

You take the 4 biggest numbers, you do not count leading zeros.  (that's 9074, you count the zero that is in the middle

0.000009074

Now you look at the 5th number, if it is 5 or bigger you round the up otherwise you do not. 

The the number is 7, it's a big one so you round up.  The last 4 becames a 5. So the answer is

0.000009075

this would be better written in scientific notation.  It is  9.075 x 10^-6

9.075 X 10^-6