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Finding the Fourth Proportional to 726.78, 1,089.21 and 418.80

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Solution

The fourth proportional to 726.78, 1,089.21 and 418.80 is: 627.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    726.78 : 1,089.21 = 418.80 : x
  2. Step 2: Convert to fraction form
    726.78/1,089.21 = 418.80/x
  3. Step 3: Cross multiply
    726.78x = 1,089.21 × 418.80
  4. Step 4: Simplify right side
    726.78x = 456,161.15
  5. Step 5: Solve for x
    x = 456,161.15/726.78
  6. Step 6: Final answer
    x = 627.65

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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.