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Finding the Fourth Proportional to 139.05, 208.50 and 78.23

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Solution

The fourth proportional to 139.05, 208.50 and 78.23 is: 117.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.05 : 208.50 = 78.23 : x
  2. Step 2: Convert to fraction form
    139.05/208.50 = 78.23/x
  3. Step 3: Cross multiply
    139.05x = 208.50 × 78.23
  4. Step 4: Simplify right side
    139.05x = 16,309.91
  5. Step 5: Solve for x
    x = 16,309.91/139.05
  6. Step 6: Final answer
    x = 117.30

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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.