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Finding the Fourth Proportional to 645.40, 890.90 and 505.56

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Solution

The fourth proportional to 645.40, 890.90 and 505.56 is: 697.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.40 : 890.90 = 505.56 : x
  2. Step 2: Convert to fraction form
    645.40/890.90 = 505.56/x
  3. Step 3: Cross multiply
    645.40x = 890.90 × 505.56
  4. Step 4: Simplify right side
    645.40x = 450,400.88
  5. Step 5: Solve for x
    x = 450,400.88/645.40
  6. Step 6: Final answer
    x = 697.87

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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.