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Finding the Fourth Proportional to 666.72, 920.16 and 386.90

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Solution

The fourth proportional to 666.72, 920.16 and 386.90 is: 533.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.72 : 920.16 = 386.90 : x
  2. Step 2: Convert to fraction form
    666.72/920.16 = 386.90/x
  3. Step 3: Cross multiply
    666.72x = 920.16 × 386.90
  4. Step 4: Simplify right side
    666.72x = 356,008.90
  5. Step 5: Solve for x
    x = 356,008.90/666.72
  6. Step 6: Final answer
    x = 533.97

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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.