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Finding the Fourth Proportional to 781.92, 1,078.65 and 487.08

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Solution

The fourth proportional to 781.92, 1,078.65 and 487.08 is: 671.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.92 : 1,078.65 = 487.08 : x
  2. Step 2: Convert to fraction form
    781.92/1,078.65 = 487.08/x
  3. Step 3: Cross multiply
    781.92x = 1,078.65 × 487.08
  4. Step 4: Simplify right side
    781.92x = 525,388.84
  5. Step 5: Solve for x
    x = 525,388.84/781.92
  6. Step 6: Final answer
    x = 671.92

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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.