Problem 6)
Scale factor is 1:6, so you are correct
Ratio of perimeters is also 1:6 because the perimeters are just the sum of the linear parts. The larger figure has a perimeter that is 6 times longer than the smaller figure.
The ratio of the areas is 1:36, you simply square both parts of the scale factor ratio. Imagine you had 2 squares. One is 1x1 and the other is 6x6. The first square has an area of 1 square unit. The second square has an area of 36 square units. We see that the larger square is 6 times larger in terms of linear side length, and 36 times larger in area compared to the smaller square.
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Problem 7)
You have the correct scale factor when you write 3:5
The ratio of perimeters is also the same at 3:5
The ratio of areas (small to big) is 9:25 after you square both parts of the scale factor.
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Problem 8)
The scale factor is 3:1 after you reduce the ratio 6:2
The ratio of perimeters is also 3:1
The ratio of areas is 9:1
