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Finding the Fourth Proportional to 1,420.45, 2,129.56 and 689.83

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Solution

The fourth proportional to 1,420.45, 2,129.56 and 689.83 is: 1,034.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.45 : 2,129.56 = 689.83 : x
  2. Step 2: Convert to fraction form
    1,420.45/2,129.56 = 689.83/x
  3. Step 3: Cross multiply
    1,420.45x = 2,129.56 × 689.83
  4. Step 4: Simplify right side
    1,420.45x = 1,469,034.37
  5. Step 5: Solve for x
    x = 1,469,034.37/1,420.45
  6. Step 6: Final answer
    x = 1,034.20

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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.