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Finding the Fourth Proportional to 666.78, 1,000.43 and 256.20

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Solution

The fourth proportional to 666.78, 1,000.43 and 256.20 is: 384.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    666.78 : 1,000.43 = 256.20 : x
  2. Step 2: Convert to fraction form
    666.78/1,000.43 = 256.20/x
  3. Step 3: Cross multiply
    666.78x = 1,000.43 × 256.20
  4. Step 4: Simplify right side
    666.78x = 256,308.89
  5. Step 5: Solve for x
    x = 256,308.89/666.78
  6. Step 6: Final answer
    x = 384.40

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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.