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Finding the Fourth Proportional to 258.28, 387.42 and 136.78

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Solution

The fourth proportional to 258.28, 387.42 and 136.78 is: 205.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.28 : 387.42 = 136.78 : x
  2. Step 2: Convert to fraction form
    258.28/387.42 = 136.78/x
  3. Step 3: Cross multiply
    258.28x = 387.42 × 136.78
  4. Step 4: Simplify right side
    258.28x = 52,991.31
  5. Step 5: Solve for x
    x = 52,991.31/258.28
  6. Step 6: Final answer
    x = 205.17

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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.