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Finding the Fourth Proportional to 911.12, 1,257.40 and 689.72

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Solution

The fourth proportional to 911.12, 1,257.40 and 689.72 is: 951.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    911.12 : 1,257.40 = 689.72 : x
  2. Step 2: Convert to fraction form
    911.12/1,257.40 = 689.72/x
  3. Step 3: Cross multiply
    911.12x = 1,257.40 × 689.72
  4. Step 4: Simplify right side
    911.12x = 867,253.93
  5. Step 5: Solve for x
    x = 867,253.93/911.12
  6. Step 6: Final answer
    x = 951.85

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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.