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Finding the Fourth Proportional to 815.17, 1,221.87 and 403.78

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Solution

The fourth proportional to 815.17, 1,221.87 and 403.78 is: 605.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.17 : 1,221.87 = 403.78 : x
  2. Step 2: Convert to fraction form
    815.17/1,221.87 = 403.78/x
  3. Step 3: Cross multiply
    815.17x = 1,221.87 × 403.78
  4. Step 4: Simplify right side
    815.17x = 493,366.67
  5. Step 5: Solve for x
    x = 493,366.67/815.17
  6. Step 6: Final answer
    x = 605.23

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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.