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Finding the Fourth Proportional to 258.20, 387.60 and 256.40

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Solution

The fourth proportional to 258.20, 387.60 and 256.40 is: 384.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.20 : 387.60 = 256.40 : x
  2. Step 2: Convert to fraction form
    258.20/387.60 = 256.40/x
  3. Step 3: Cross multiply
    258.20x = 387.60 × 256.40
  4. Step 4: Simplify right side
    258.20x = 99,380.64
  5. Step 5: Solve for x
    x = 99,380.64/258.20
  6. Step 6: Final answer
    x = 384.90

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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.