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Finding the Fourth Proportional to 813.12, 1,218.78 and 620.34

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Solution

The fourth proportional to 813.12, 1,218.78 and 620.34 is: 929.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.12 : 1,218.78 = 620.34 : x
  2. Step 2: Convert to fraction form
    813.12/1,218.78 = 620.34/x
  3. Step 3: Cross multiply
    813.12x = 1,218.78 × 620.34
  4. Step 4: Simplify right side
    813.12x = 756,057.99
  5. Step 5: Solve for x
    x = 756,057.99/813.12
  6. Step 6: Final answer
    x = 929.82

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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.