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Finding the Fourth Proportional to 664.09, 997.20 and 390.40

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Solution

The fourth proportional to 664.09, 997.20 and 390.40 is: 586.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    664.09 : 997.20 = 390.40 : x
  2. Step 2: Convert to fraction form
    664.09/997.20 = 390.40/x
  3. Step 3: Cross multiply
    664.09x = 997.20 × 390.40
  4. Step 4: Simplify right side
    664.09x = 389,306.88
  5. Step 5: Solve for x
    x = 389,306.88/664.09
  6. Step 6: Final answer
    x = 586.23

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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.