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Finding the Fourth Proportional to 486.40, 729.61 and 139.72

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Solution

The fourth proportional to 486.40, 729.61 and 139.72 is: 209.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    486.40 : 729.61 = 139.72 : x
  2. Step 2: Convert to fraction form
    486.40/729.61 = 139.72/x
  3. Step 3: Cross multiply
    486.40x = 729.61 × 139.72
  4. Step 4: Simplify right side
    486.40x = 101,942.00
  5. Step 5: Solve for x
    x = 101,942.00/486.40
  6. Step 6: Final answer
    x = 209.58

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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.