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Finding the Fourth Proportional to 1,420.47, 2,129.81 and 689.31

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Solution

The fourth proportional to 1,420.47, 2,129.81 and 689.31 is: 1,033.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.47 : 2,129.81 = 689.31 : x
  2. Step 2: Convert to fraction form
    1,420.47/2,129.81 = 689.31/x
  3. Step 3: Cross multiply
    1,420.47x = 2,129.81 × 689.31
  4. Step 4: Simplify right side
    1,420.47x = 1,468,095.88
  5. Step 5: Solve for x
    x = 1,468,095.88/1,420.47
  6. Step 6: Final answer
    x = 1,033.53

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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.