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Finding the Fourth Proportional to 811.11, 1,215.76 and 399.38

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Solution

The fourth proportional to 811.11, 1,215.76 and 399.38 is: 598.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.11 : 1,215.76 = 399.38 : x
  2. Step 2: Convert to fraction form
    811.11/1,215.76 = 399.38/x
  3. Step 3: Cross multiply
    811.11x = 1,215.76 × 399.38
  4. Step 4: Simplify right side
    811.11x = 485,550.74
  5. Step 5: Solve for x
    x = 485,550.74/811.11
  6. Step 6: Final answer
    x = 598.62

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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.