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Finding the Fourth Proportional to 139.22, 208.80 and 70.78

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Solution

The fourth proportional to 139.22, 208.80 and 70.78 is: 106.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.22 : 208.80 = 70.78 : x
  2. Step 2: Convert to fraction form
    139.22/208.80 = 70.78/x
  3. Step 3: Cross multiply
    139.22x = 208.80 × 70.78
  4. Step 4: Simplify right side
    139.22x = 14,778.86
  5. Step 5: Solve for x
    x = 14,778.86/139.22
  6. Step 6: Final answer
    x = 106.15

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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.