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Finding the Fourth Proportional to 812.20, 1,120.80 and 517.72

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Solution

The fourth proportional to 812.20, 1,120.80 and 517.72 is: 714.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.20 : 1,120.80 = 517.72 : x
  2. Step 2: Convert to fraction form
    812.20/1,120.80 = 517.72/x
  3. Step 3: Cross multiply
    812.20x = 1,120.80 × 517.72
  4. Step 4: Simplify right side
    812.20x = 580,260.58
  5. Step 5: Solve for x
    x = 580,260.58/812.20
  6. Step 6: Final answer
    x = 714.43

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.