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Finding the Fourth Proportional to 787.68, 1,086.90 and 456.20

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Solution

The fourth proportional to 787.68, 1,086.90 and 456.20 is: 629.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.68 : 1,086.90 = 456.20 : x
  2. Step 2: Convert to fraction form
    787.68/1,086.90 = 456.20/x
  3. Step 3: Cross multiply
    787.68x = 1,086.90 × 456.20
  4. Step 4: Simplify right side
    787.68x = 495,843.78
  5. Step 5: Solve for x
    x = 495,843.78/787.68
  6. Step 6: Final answer
    x = 629.50

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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.