Câu 3: trang 170 - toán tiếng anh lớp 5A metal block has a volume of 3,2cm3and a weight...

Using the formula: weight = volume * density, we can find the weight of the block with a volume of 4.5cm3. Since the density of the metal block is 7g/cm3, the weight of the block can be calculated as 4.5cm3 * 7g/cm3 = 31.5g.

Let x be the weight of the block with a volume of 4.5cm3. According to the given information, we can set up a proportion: 3.2cm3/22.4g = 4.5cm3/x. Solving for x, we get x = 31.5g.

Since the density of the metal block is 7g/cm3, the weight of the block with a volume of 4.5cm3 can be calculated by multiplying the volume by the density: weight = volume * density = 4.5cm3 * 7g/cm3 = 31.5g.

The density of the metal block can be calculated by dividing its weight by its volume: density = weight/volume = 22.4g/3.2cm3 = 7g/cm3. Therefore, a block of the same metal with a volume of 4.5cm3 will weigh 4.5cm3 * 7g/cm3 = 31.5g.