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Finding the Fourth Proportional to 258.46, 387.45 and 128.38

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Solution

The fourth proportional to 258.46, 387.45 and 128.38 is: 192.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.46 : 387.45 = 128.38 : x
  2. Step 2: Convert to fraction form
    258.46/387.45 = 128.38/x
  3. Step 3: Cross multiply
    258.46x = 387.45 × 128.38
  4. Step 4: Simplify right side
    258.46x = 49,740.83
  5. Step 5: Solve for x
    x = 49,740.83/258.46
  6. Step 6: Final answer
    x = 192.45

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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.