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Finding the Fourth Proportional to 1,389, 2,083.50 and 811.47

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Solution

The fourth proportional to 1,389, 2,083.50 and 811.47 is: 1,217.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389 : 2,083.50 = 811.47 : x
  2. Step 2: Convert to fraction form
    1,389/2,083.50 = 811.47/x
  3. Step 3: Cross multiply
    1,389x = 2,083.50 × 811.47
  4. Step 4: Simplify right side
    1,389x = 1,690,697.75
  5. Step 5: Solve for x
    x = 1,690,697.75/1,389
  6. Step 6: Final answer
    x = 1,217.21

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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.