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Finding the Fourth Proportional to 812.84, 1,217.70 and 638.69

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Solution

The fourth proportional to 812.84, 1,217.70 and 638.69 is: 956.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    812.84 : 1,217.70 = 638.69 : x
  2. Step 2: Convert to fraction form
    812.84/1,217.70 = 638.69/x
  3. Step 3: Cross multiply
    812.84x = 1,217.70 × 638.69
  4. Step 4: Simplify right side
    812.84x = 777,726.72
  5. Step 5: Solve for x
    x = 777,726.72/812.84
  6. Step 6: Final answer
    x = 956.81

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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.