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Finding the Fourth Proportional to 644.80, 890.34 and 515.20

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Solution

The fourth proportional to 644.80, 890.34 and 515.20 is: 711.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    644.80 : 890.34 = 515.20 : x
  2. Step 2: Convert to fraction form
    644.80/890.34 = 515.20/x
  3. Step 3: Cross multiply
    644.80x = 890.34 × 515.20
  4. Step 4: Simplify right side
    644.80x = 458,703.17
  5. Step 5: Solve for x
    x = 458,703.17/644.80
  6. Step 6: Final answer
    x = 711.39

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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.