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Finding the Fourth Proportional to 729.11, 1,091.72 and 420.50

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Solution

The fourth proportional to 729.11, 1,091.72 and 420.50 is: 629.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    729.11 : 1,091.72 = 420.50 : x
  2. Step 2: Convert to fraction form
    729.11/1,091.72 = 420.50/x
  3. Step 3: Cross multiply
    729.11x = 1,091.72 × 420.50
  4. Step 4: Simplify right side
    729.11x = 459,060.70
  5. Step 5: Solve for x
    x = 459,060.70/729.11
  6. Step 6: Final answer
    x = 629.62

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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.