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Finding the Fourth Proportional to 789.78, 1,089.78 and 458.15

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Solution

The fourth proportional to 789.78, 1,089.78 and 458.15 is: 632.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    789.78 : 1,089.78 = 458.15 : x
  2. Step 2: Convert to fraction form
    789.78/1,089.78 = 458.15/x
  3. Step 3: Cross multiply
    789.78x = 1,089.78 × 458.15
  4. Step 4: Simplify right side
    789.78x = 499,277.26
  5. Step 5: Solve for x
    x = 499,277.26/789.78
  6. Step 6: Final answer
    x = 632.17

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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.