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Finding the Fourth Proportional to 1,121.68, 1,682.31 and 391.13

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Solution

The fourth proportional to 1,121.68, 1,682.31 and 391.13 is: 586.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,121.68 : 1,682.31 = 391.13 : x
  2. Step 2: Convert to fraction form
    1,121.68/1,682.31 = 391.13/x
  3. Step 3: Cross multiply
    1,121.68x = 1,682.31 × 391.13
  4. Step 4: Simplify right side
    1,121.68x = 658,001.91
  5. Step 5: Solve for x
    x = 658,001.91/1,121.68
  6. Step 6: Final answer
    x = 586.62

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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.