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Finding the Fourth Proportional to 258.60, 387.94 and 128.85

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Solution

The fourth proportional to 258.60, 387.94 and 128.85 is: 193.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.60 : 387.94 = 128.85 : x
  2. Step 2: Convert to fraction form
    258.60/387.94 = 128.85/x
  3. Step 3: Cross multiply
    258.60x = 387.94 × 128.85
  4. Step 4: Simplify right side
    258.60x = 49,986.07
  5. Step 5: Solve for x
    x = 49,986.07/258.60
  6. Step 6: Final answer
    x = 193.29

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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.