Answer:
Null Hypothesis,  :
 :  = 1,100 square feet
 = 1,100 square feet 
Alternate Hypothesis,  :
 :  < 1,100 square feet
 < 1,100 square feet 
Step-by-step explanation:
We are given that the mean area of several thousand apartments in a new development is advertised to be 1,100 square feet. 
A consumer advocate has received numerous complaints that the apartments are smaller than advertised.
<u><em>Let </em></u> <u><em> = mean area of several apartments.</em></u>
<u><em> = mean area of several apartments.</em></u>
So, Null Hypothesis,  :
 :  = 1,100 square feet
 = 1,100 square feet 
Alternate Hypothesis,  :
 :  < 1,100 square feet
 < 1,100 square feet 
Here, <u>null hypothesis states that</u> the mean area of apartments are same as advertised.
On the other hand, <u>alternate hypothesis states that</u> the mean area of apartments are smaller than advertised.
So, this would be the appropriate null and the alternative hypothesis to test this claim.