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Finding the Fourth Proportional to 286.12, 428.72 and 258.78

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Solution

The fourth proportional to 286.12, 428.72 and 258.78 is: 387.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    286.12 : 428.72 = 258.78 : x
  2. Step 2: Convert to fraction form
    286.12/428.72 = 258.78/x
  3. Step 3: Cross multiply
    286.12x = 428.72 × 258.78
  4. Step 4: Simplify right side
    286.12x = 110,942.87
  5. Step 5: Solve for x
    x = 110,942.87/286.12
  6. Step 6: Final answer
    x = 387.75

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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.