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Finding the Fourth Proportional to 669.90, 1,005.09 and 207.80

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Solution

The fourth proportional to 669.90, 1,005.09 and 207.80 is: 311.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    669.90 : 1,005.09 = 207.80 : x
  2. Step 2: Convert to fraction form
    669.90/1,005.09 = 207.80/x
  3. Step 3: Cross multiply
    669.90x = 1,005.09 × 207.80
  4. Step 4: Simplify right side
    669.90x = 208,856.84
  5. Step 5: Solve for x
    x = 208,856.84/669.90
  6. Step 6: Final answer
    x = 311.77

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.