Verified Answer :

The answer is 0.7. Since the formula of the z-score is the difference of the score (x) and the mean divided by the standard deviation (SD)...
 
z= [ (x-mean)/SD ] 

You simply substitute the values given.

z = (11-9)/2.8
z=2/2.8
z=0.714

Then round it to the nearest tenth...

z- = 0.7