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Finding the Fourth Proportional to 645.20, 890.69 and 505.07

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Solution

The fourth proportional to 645.20, 890.69 and 505.07 is: 697.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.20 : 890.69 = 505.07 : x
  2. Step 2: Convert to fraction form
    645.20/890.69 = 505.07/x
  3. Step 3: Cross multiply
    645.20x = 890.69 × 505.07
  4. Step 4: Simplify right side
    645.20x = 449,860.80
  5. Step 5: Solve for x
    x = 449,860.80/645.20
  6. Step 6: Final answer
    x = 697.24

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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.