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Finding the Fourth Proportional to 138.72, 208.08 and 70.28

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Solution

The fourth proportional to 138.72, 208.08 and 70.28 is: 105.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.72 : 208.08 = 70.28 : x
  2. Step 2: Convert to fraction form
    138.72/208.08 = 70.28/x
  3. Step 3: Cross multiply
    138.72x = 208.08 × 70.28
  4. Step 4: Simplify right side
    138.72x = 14,623.86
  5. Step 5: Solve for x
    x = 14,623.86/138.72
  6. Step 6: Final answer
    x = 105.42

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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.