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Finding the Fourth Proportional to 811.22, 1,215.81 and 400.85

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Solution

The fourth proportional to 811.22, 1,215.81 and 400.85 is: 600.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.22 : 1,215.81 = 400.85 : x
  2. Step 2: Convert to fraction form
    811.22/1,215.81 = 400.85/x
  3. Step 3: Cross multiply
    811.22x = 1,215.81 × 400.85
  4. Step 4: Simplify right side
    811.22x = 487,355.92
  5. Step 5: Solve for x
    x = 487,355.92/811.22
  6. Step 6: Final answer
    x = 600.77

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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.