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Finding the Fourth Proportional to 258.87, 387.94 and 128.74

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Solution

The fourth proportional to 258.87, 387.94 and 128.74 is: 192.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.87 : 387.94 = 128.74 : x
  2. Step 2: Convert to fraction form
    258.87/387.94 = 128.74/x
  3. Step 3: Cross multiply
    258.87x = 387.94 × 128.74
  4. Step 4: Simplify right side
    258.87x = 49,944.21
  5. Step 5: Solve for x
    x = 49,944.21/258.87
  6. Step 6: Final answer
    x = 192.93

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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.