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Finding the Fourth Proportional to 666.85, 920.45 and 387.21

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Solution

The fourth proportional to 666.85, 920.45 and 387.21 is: 534.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.85 : 920.45 = 387.21 : x
  2. Step 2: Convert to fraction form
    666.85/920.45 = 387.21/x
  3. Step 3: Cross multiply
    666.85x = 920.45 × 387.21
  4. Step 4: Simplify right side
    666.85x = 356,400.91
  5. Step 5: Solve for x
    x = 356,400.91/666.85
  6. Step 6: Final answer
    x = 534.46

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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.