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Finding the Fourth Proportional to 787.92, 1,087.20 and 438.60

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Solution

The fourth proportional to 787.92, 1,087.20 and 438.60 is: 605.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    787.92 : 1,087.20 = 438.60 : x
  2. Step 2: Convert to fraction form
    787.92/1,087.20 = 438.60/x
  3. Step 3: Cross multiply
    787.92x = 1,087.20 × 438.60
  4. Step 4: Simplify right side
    787.92x = 476,845.92
  5. Step 5: Solve for x
    x = 476,845.92/787.92
  6. Step 6: Final answer
    x = 605.20

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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.