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Finding the Fourth Proportional to 1,280.71, 1,921.53 and 865.85

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Solution

The fourth proportional to 1,280.71, 1,921.53 and 865.85 is: 1,299.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,280.71 : 1,921.53 = 865.85 : x
  2. Step 2: Convert to fraction form
    1,280.71/1,921.53 = 865.85/x
  3. Step 3: Cross multiply
    1,280.71x = 1,921.53 × 865.85
  4. Step 4: Simplify right side
    1,280.71x = 1,663,756.75
  5. Step 5: Solve for x
    x = 1,663,756.75/1,280.71
  6. Step 6: Final answer
    x = 1,299.09

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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.