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Finding the Fourth Proportional to 689.50, 951.50 and 390.72

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Solution

The fourth proportional to 689.50, 951.50 and 390.72 is: 539.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.50 : 951.50 = 390.72 : x
  2. Step 2: Convert to fraction form
    689.50/951.50 = 390.72/x
  3. Step 3: Cross multiply
    689.50x = 951.50 × 390.72
  4. Step 4: Simplify right side
    689.50x = 371,772.43
  5. Step 5: Solve for x
    x = 371,772.43/689.50
  6. Step 6: Final answer
    x = 539.19

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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.