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Finding the Fourth Proportional to 689.54, 951.58 and 390.80

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Solution

The fourth proportional to 689.54, 951.58 and 390.80 is: 539.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.54 : 951.58 = 390.80 : x
  2. Step 2: Convert to fraction form
    689.54/951.58 = 390.80/x
  3. Step 3: Cross multiply
    689.54x = 951.58 × 390.80
  4. Step 4: Simplify right side
    689.54x = 371,878.87
  5. Step 5: Solve for x
    x = 371,878.87/689.54
  6. Step 6: Final answer
    x = 539.31

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.