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Finding the Fourth Proportional to 258.78, 387.87 and 212.61

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Solution

The fourth proportional to 258.78, 387.87 and 212.61 is: 318.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    258.78 : 387.87 = 212.61 : x
  2. Step 2: Convert to fraction form
    258.78/387.87 = 212.61/x
  3. Step 3: Cross multiply
    258.78x = 387.87 × 212.61
  4. Step 4: Simplify right side
    258.78x = 82,465.04
  5. Step 5: Solve for x
    x = 82,465.04/258.78
  6. Step 6: Final answer
    x = 318.67

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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.