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Finding the Fourth Proportional to 139.63, 209.44 and 78.76

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Solution

The fourth proportional to 139.63, 209.44 and 78.76 is: 118.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.63 : 209.44 = 78.76 : x
  2. Step 2: Convert to fraction form
    139.63/209.44 = 78.76/x
  3. Step 3: Cross multiply
    139.63x = 209.44 × 78.76
  4. Step 4: Simplify right side
    139.63x = 16,495.17
  5. Step 5: Solve for x
    x = 16,495.17/139.63
  6. Step 6: Final answer
    x = 118.14

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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.