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Finding the Fourth Proportional to 813, 1,211.78 and 765.66

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Solution

The fourth proportional to 813, 1,211.78 and 765.66 is: 1,141.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    813 : 1,211.78 = 765.66 : x
  2. Step 2: Convert to fraction form
    813/1,211.78 = 765.66/x
  3. Step 3: Cross multiply
    813x = 1,211.78 × 765.66
  4. Step 4: Simplify right side
    813x = 927,811.47
  5. Step 5: Solve for x
    x = 927,811.47/813
  6. Step 6: Final answer
    x = 1,141.22

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.