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Finding the Fourth Proportional to 827.34, 1,239.86 and 643.90

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Solution

The fourth proportional to 827.34, 1,239.86 and 643.90 is: 964.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    827.34 : 1,239.86 = 643.90 : x
  2. Step 2: Convert to fraction form
    827.34/1,239.86 = 643.90/x
  3. Step 3: Cross multiply
    827.34x = 1,239.86 × 643.90
  4. Step 4: Simplify right side
    827.34x = 798,345.85
  5. Step 5: Solve for x
    x = 798,345.85/827.34
  6. Step 6: Final answer
    x = 964.95

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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.