Area is Length x width.
Area = 4x * 5
Area = 20x
Replace A in the inequality:
Now you have 100 <= 20x <= 1,000
Now solve for x by dividing all 3 by 20:
5 <= x <=50
Check to see if they are viable:
4(5) x 5 = 20 x 5 = 100
4(50) x 5 = 200 x 5 = 1,000
Since the lowest number equals 100 and the largest number equals 1,000 all values of x would be viable. The answer is YES.