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Finding the Fourth Proportional to 689.76, 951.64 and 390.98

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Solution

The fourth proportional to 689.76, 951.64 and 390.98 is: 539.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.76 : 951.64 = 390.98 : x
  2. Step 2: Convert to fraction form
    689.76/951.64 = 390.98/x
  3. Step 3: Cross multiply
    689.76x = 951.64 × 390.98
  4. Step 4: Simplify right side
    689.76x = 372,068.94
  5. Step 5: Solve for x
    x = 372,068.94/689.76
  6. Step 6: Final answer
    x = 539.42

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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.