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Finding the Fourth Proportional to 686.40, 1,029.78 and 199.44

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Solution

The fourth proportional to 686.40, 1,029.78 and 199.44 is: 299.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.40 : 1,029.78 = 199.44 : x
  2. Step 2: Convert to fraction form
    686.40/1,029.78 = 199.44/x
  3. Step 3: Cross multiply
    686.40x = 1,029.78 × 199.44
  4. Step 4: Simplify right side
    686.40x = 205,379.32
  5. Step 5: Solve for x
    x = 205,379.32/686.40
  6. Step 6: Final answer
    x = 299.21

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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.