1. According to the meaning of the question, the garden is 5m in diameter and the road width is1m.. Draw a schematic diagram as shown in the attached figure. The radius of the big circle is 3.5m and the radius of the small circle is 2.5m.. The ratio is 1:250, so the radius of the major circle is 1.4cm and the radius of the minor circle is 1cm. The actual paving area (the orange part in the figure) is the large circle area minus the small circle area: 3.14× 3.5× 3.5-3.14× 2.5 = 3.14× 6 =18.84m2.

2. given the length L=240cm, find the width w: l/w = 3/2-> w = l× 2/3 = 160cm, that is, the width is160cm.

(L-W)/W=50%, that is, the length is 50% more than the width.

3. The volume of toothpaste used every day is 3× 3× 3× 20× 2 =1080mm3 =1.08cm3.

Days of use: 45/ 1.08≈4 1.667, so this toothpaste is estimated to last for 42 days.

Four. 9 * 6 = 9× 2-6 = 12

Verb (abbreviation of verb) Map scale: 3cm/240km = 3cm/24000000cm =1:800000.

The distance from Guangzhou to Beijing measured on the map is 22.5cm, and the actual distance is s, so: 22.5/S= 1:8000000,

S =180000000 cm = 1800km, so the actual distance from Guangzhou to Beijing is about1800 km.

6. According to the ratio of mercuric chloride to distilled water, distilled water is 50 times of mercuric chloride, and 30g mercuric chloride needs distilled water.

30g×50= 1500g

(1). There are two changes, one is that Zhang Hua's age is changing, and the other is that Zhang Hua's weight is changing.

(2). 1 year gained 3.5kg every six months, 1 year gained 3kg, gained 7.5kg at 2 years old and gained 9.5kg at 6 years old. ..