(1) On the map, the distance from Xiaohua's home to school is 1.2cm, and the scale is:1.2cm: 300m =1.2cm: 30000cm =1:25000;

(2) 1÷ 125000=25000 (cm),

25000cm = 250m；

(3) The measured distance from the library to the Oriental Plaza via the school is: 2.4+3=5.4 cm,

5.4÷125000 =135000 (cm),

135000cm = 1350m；

Answer: Actually walked1350m;

(4) The distance from Xiaohua Jiajing School to Oriental Plaza is: 1.2+3=4.2 cm.

4.2÷125000 =105000 (cm),

105000m =1050m,

1050÷60= 17.5 (minutes);

A:* * * * line 17.5 minutes;

⑤400 meters = 40,000 centimeters,

40000× 125000= 1.6 (cm);

As shown in the figure:

So the answers are: 1.2, 1: 25000, 1.250.