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Finding the Fourth Proportional to 1,439.78, 2,160.47 and 781.65

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Solution

The fourth proportional to 1,439.78, 2,160.47 and 781.65 is: 1,172.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,439.78 : 2,160.47 = 781.65 : x
  2. Step 2: Convert to fraction form
    1,439.78/2,160.47 = 781.65/x
  3. Step 3: Cross multiply
    1,439.78x = 2,160.47 × 781.65
  4. Step 4: Simplify right side
    1,439.78x = 1,688,733.33
  5. Step 5: Solve for x
    x = 1,688,733.33/1,439.78
  6. Step 6: Final answer
    x = 1,172.91

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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.