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Finding the Fourth Proportional to 840.78, 1,259.28 and 820.14

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Solution

The fourth proportional to 840.78, 1,259.28 and 820.14 is: 1,228.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.78 : 1,259.28 = 820.14 : x
  2. Step 2: Convert to fraction form
    840.78/1,259.28 = 820.14/x
  3. Step 3: Cross multiply
    840.78x = 1,259.28 × 820.14
  4. Step 4: Simplify right side
    840.78x = 1,032,785.90
  5. Step 5: Solve for x
    x = 1,032,785.90/840.78
  6. Step 6: Final answer
    x = 1,228.37

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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.