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Finding the Fourth Proportional to 781.18, 1,078.20 and 470.68

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Solution

The fourth proportional to 781.18, 1,078.20 and 470.68 is: 649.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.18 : 1,078.20 = 470.68 : x
  2. Step 2: Convert to fraction form
    781.18/1,078.20 = 470.68/x
  3. Step 3: Cross multiply
    781.18x = 1,078.20 × 470.68
  4. Step 4: Simplify right side
    781.18x = 507,487.18
  5. Step 5: Solve for x
    x = 507,487.18/781.18
  6. Step 6: Final answer
    x = 649.64

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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.