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Finding the Fourth Proportional to 666.99, 920.43 and 405

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Solution

The fourth proportional to 666.99, 920.43 and 405 is: 558.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.99 : 920.43 = 405 : x
  2. Step 2: Convert to fraction form
    666.99/920.43 = 405/x
  3. Step 3: Cross multiply
    666.99x = 920.43 × 405
  4. Step 4: Simplify right side
    666.99x = 372,774.15
  5. Step 5: Solve for x
    x = 372,774.15/666.99
  6. Step 6: Final answer
    x = 558.89

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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.