No. 30*900 is 27000 plus 3*900 is 2700 which is 29700. This approximation is completely off from 2750 and therefore your approximation is an unreasonable answer.
Since it takes 48 minutes to walk 6 laps, you can divide 48 by 6 to get how long it takes for him to walk one lap. Mickey will take 8 minutes to walk 1 lap.
