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Finding the Fourth Proportional to 258.49, 387.57 and 128.47

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Solution

The fourth proportional to 258.49, 387.57 and 128.47 is: 192.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.49 : 387.57 = 128.47 : x
  2. Step 2: Convert to fraction form
    258.49/387.57 = 128.47/x
  3. Step 3: Cross multiply
    258.49x = 387.57 × 128.47
  4. Step 4: Simplify right side
    258.49x = 49,791.12
  5. Step 5: Solve for x
    x = 49,791.12/258.49
  6. Step 6: Final answer
    x = 192.62

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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.