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Finding the Fourth Proportional to 139.48, 208.95 and 78.43

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Solution

The fourth proportional to 139.48, 208.95 and 78.43 is: 117.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.48 : 208.95 = 78.43 : x
  2. Step 2: Convert to fraction form
    139.48/208.95 = 78.43/x
  3. Step 3: Cross multiply
    139.48x = 208.95 × 78.43
  4. Step 4: Simplify right side
    139.48x = 16,387.95
  5. Step 5: Solve for x
    x = 16,387.95/139.48
  6. Step 6: Final answer
    x = 117.49

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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.