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Finding the Fourth Proportional to 686.40, 1,029.77 and 378.60

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Solution

The fourth proportional to 686.40, 1,029.77 and 378.60 is: 567.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.40 : 1,029.77 = 378.60 : x
  2. Step 2: Convert to fraction form
    686.40/1,029.77 = 378.60/x
  3. Step 3: Cross multiply
    686.40x = 1,029.77 × 378.60
  4. Step 4: Simplify right side
    686.40x = 389,869.03
  5. Step 5: Solve for x
    x = 389,869.03/686.40
  6. Step 6: Final answer
    x = 567.99

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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.