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Finding the Fourth Proportional to 645.80, 890.20 and 396.66

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Solution

The fourth proportional to 645.80, 890.20 and 396.66 is: 546.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.80 : 890.20 = 396.66 : x
  2. Step 2: Convert to fraction form
    645.80/890.20 = 396.66/x
  3. Step 3: Cross multiply
    645.80x = 890.20 × 396.66
  4. Step 4: Simplify right side
    645.80x = 353,106.73
  5. Step 5: Solve for x
    x = 353,106.73/645.80
  6. Step 6: Final answer
    x = 546.77

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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.