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Finding the Fourth Proportional to 138.72, 208.28 and 70.29

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Solution

The fourth proportional to 138.72, 208.28 and 70.29 is: 105.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.72 : 208.28 = 70.29 : x
  2. Step 2: Convert to fraction form
    138.72/208.28 = 70.29/x
  3. Step 3: Cross multiply
    138.72x = 208.28 × 70.29
  4. Step 4: Simplify right side
    138.72x = 14,640.75
  5. Step 5: Solve for x
    x = 14,640.75/138.72
  6. Step 6: Final answer
    x = 105.54

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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.