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Finding the Fourth Proportional to 861.98, 1,189.56 and 489

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Solution

The fourth proportional to 861.98, 1,189.56 and 489 is: 674.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    861.98 : 1,189.56 = 489 : x
  2. Step 2: Convert to fraction form
    861.98/1,189.56 = 489/x
  3. Step 3: Cross multiply
    861.98x = 1,189.56 × 489
  4. Step 4: Simplify right side
    861.98x = 581,694.84
  5. Step 5: Solve for x
    x = 581,694.84/861.98
  6. Step 6: Final answer
    x = 674.84

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.