Twenty more than four times a number is equal to the difference between 139 and three times the number. Find the number.
1 answer:
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Answer:
- The scale factor is one-half
- The perimeter of the model is the product of the scale factor and the perimeter of the original rectangle
-The area of the reduced figure is (1/2)^2 = 1/4 times the area of the original figure
Step-by-step explanation:
The ratio of the length of the original rectangle to that of the reduced rectangle is 6 to 3, or a factor of 1/2. The ratio of the width of the original rectangle to that of the reduced rectangle is 2 to 1, or, again, a factor of 1/2. So, because this ratio of 1/2 is constant, we know the total scale factor is 1/2, making B correct.
The perimeter of a rectangle is: , where l is the length and w is the width. The perimeter of the reduced figure is: P = 2 * 3 + 2 * 1 = 6 + 2 = 8 units. The perimeter of the original figure is: P = 2 * 6 + 2 * 2 = 12 + 4 = 16 units.
Notice that 16 * (1/2) = 8, which means that the perimeter of the scale-factored, reduced rectangle is "the product of the scale factor (which is 1/2) and the perimeter of the original rectangle (which is 16)". So, C is correct.
The area of a rectangle is: , where l is the length and w is the width. The area of the reduced figure is: A = 3 * 1 = 3 units squared. The area of the original figure is: A = 6 * 2 = 12 units squared.
Notice that 12 * (1/4) = 3, which means that E is correct, but D is wrong.
Hope this helps!