Answer:
-  Minneapolis has a population of 383,000
 
- Oakland has a population of 391,000
 
- Wichita has a population of 382,000
 
Explanation:
Minneapolis has a population of 382,578
Oakland has a population of 390,724
Wichita has a population of 382,368
All three cities have 6 places of population. 
Round off: If round off digit is more than or equal to 5 then it increases previous digit by 1 . 
If round off digit is less than 5 then doesn't change in previous digit. 
Round off all population to thousands. 
First Round off the number 382,578 to thousands place 
 382,578 ⇒ hundreds digit is 5. So, thousands place digit will increase by 1 
382,578 ⇒ 383,000
390,724 ⇒ hundreds digit is 7. So, thousands place digit will increase by 1 
390,724 ⇒ 391,000
382,368 ⇒ hundreds digit is 3. So, thousands place digit will not change. 
382,368 ⇒ 382,000
After round off the population:- 
-  Minneapolis has a population of 383,000
 
- Oakland has a population of 391,000
 
- Wichita has a population of 382,000
 
All three cities are different population.