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Finding the Fourth Proportional to 139.13, 208.66 and 47.80

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Solution

The fourth proportional to 139.13, 208.66 and 47.80 is: 71.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.13 : 208.66 = 47.80 : x
  2. Step 2: Convert to fraction form
    139.13/208.66 = 47.80/x
  3. Step 3: Cross multiply
    139.13x = 208.66 × 47.80
  4. Step 4: Simplify right side
    139.13x = 9,973.95
  5. Step 5: Solve for x
    x = 9,973.95/139.13
  6. Step 6: Final answer
    x = 71.69

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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.