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Finding the Fourth Proportional to 871.65, 1,305.12 and 638.78

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Solution

The fourth proportional to 871.65, 1,305.12 and 638.78 is: 956.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.65 : 1,305.12 = 638.78 : x
  2. Step 2: Convert to fraction form
    871.65/1,305.12 = 638.78/x
  3. Step 3: Cross multiply
    871.65x = 1,305.12 × 638.78
  4. Step 4: Simplify right side
    871.65x = 833,678.03
  5. Step 5: Solve for x
    x = 833,678.03/871.65
  6. Step 6: Final answer
    x = 956.44

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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.