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Finding the Fourth Proportional to 686.12, 1,029.90 and 253.40

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Solution

The fourth proportional to 686.12, 1,029.90 and 253.40 is: 380.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.12 : 1,029.90 = 253.40 : x
  2. Step 2: Convert to fraction form
    686.12/1,029.90 = 253.40/x
  3. Step 3: Cross multiply
    686.12x = 1,029.90 × 253.40
  4. Step 4: Simplify right side
    686.12x = 260,976.66
  5. Step 5: Solve for x
    x = 260,976.66/686.12
  6. Step 6: Final answer
    x = 380.37

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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.