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Finding the Fourth Proportional to 666.78, 999.42 and 319.86

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Solution

The fourth proportional to 666.78, 999.42 and 319.86 is: 479.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.78 : 999.42 = 319.86 : x
  2. Step 2: Convert to fraction form
    666.78/999.42 = 319.86/x
  3. Step 3: Cross multiply
    666.78x = 999.42 × 319.86
  4. Step 4: Simplify right side
    666.78x = 319,674.48
  5. Step 5: Solve for x
    x = 319,674.48/666.78
  6. Step 6: Final answer
    x = 479.43

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.