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Finding the Fourth Proportional to 1,378.92, 2,068.38 and 686.28

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Solution

The fourth proportional to 1,378.92, 2,068.38 and 686.28 is: 1,029.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,378.92 : 2,068.38 = 686.28 : x
  2. Step 2: Convert to fraction form
    1,378.92/2,068.38 = 686.28/x
  3. Step 3: Cross multiply
    1,378.92x = 2,068.38 × 686.28
  4. Step 4: Simplify right side
    1,378.92x = 1,419,487.83
  5. Step 5: Solve for x
    x = 1,419,487.83/1,378.92
  6. Step 6: Final answer
    x = 1,029.42

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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.