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Finding the Fourth Proportional to 720.78, 1,083.78 and 663.66

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Solution

The fourth proportional to 720.78, 1,083.78 and 663.66 is: 997.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.78 : 1,083.78 = 663.66 : x
  2. Step 2: Convert to fraction form
    720.78/1,083.78 = 663.66/x
  3. Step 3: Cross multiply
    720.78x = 1,083.78 × 663.66
  4. Step 4: Simplify right side
    720.78x = 719,261.43
  5. Step 5: Solve for x
    x = 719,261.43/720.78
  6. Step 6: Final answer
    x = 997.89

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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.