Answer:
By about 28% has the city grown over the past ten years.
Explanation:
Ten years ago, the city's population was 249,583. Its current population is 318,270. By about 28% has the city grown over the past ten years. [ Solution: Population of the city before 10 years = 249583; Current population = 318270; Population grown =318270-249583 = 68687; 68687/249583 = 0.2752; 0.2752 x 100 = 27.52%. ]