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Finding the Fourth Proportional to 670.40, 1,005.40 and 439.28

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Solution

The fourth proportional to 670.40, 1,005.40 and 439.28 is: 658.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    670.40 : 1,005.40 = 439.28 : x
  2. Step 2: Convert to fraction form
    670.40/1,005.40 = 439.28/x
  3. Step 3: Cross multiply
    670.40x = 1,005.40 × 439.28
  4. Step 4: Simplify right side
    670.40x = 441,652.11
  5. Step 5: Solve for x
    x = 441,652.11/670.40
  6. Step 6: Final answer
    x = 658.79

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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.