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Finding the Fourth Proportional to 787.78, 1,087.14 and 493.21

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Solution

The fourth proportional to 787.78, 1,087.14 and 493.21 is: 680.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.78 : 1,087.14 = 493.21 : x
  2. Step 2: Convert to fraction form
    787.78/1,087.14 = 493.21/x
  3. Step 3: Cross multiply
    787.78x = 1,087.14 × 493.21
  4. Step 4: Simplify right side
    787.78x = 536,188.32
  5. Step 5: Solve for x
    x = 536,188.32/787.78
  6. Step 6: Final answer
    x = 680.63

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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.