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Finding the Fourth Proportional to 752.20, 1,128.30 and 387.70

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Solution

The fourth proportional to 752.20, 1,128.30 and 387.70 is: 581.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    752.20 : 1,128.30 = 387.70 : x
  2. Step 2: Convert to fraction form
    752.20/1,128.30 = 387.70/x
  3. Step 3: Cross multiply
    752.20x = 1,128.30 × 387.70
  4. Step 4: Simplify right side
    752.20x = 437,441.91
  5. Step 5: Solve for x
    x = 437,441.91/752.20
  6. Step 6: Final answer
    x = 581.55

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.