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Finding the Fourth Proportional to 139.55, 208.92 and 90.64

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Solution

The fourth proportional to 139.55, 208.92 and 90.64 is: 135.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.55 : 208.92 = 90.64 : x
  2. Step 2: Convert to fraction form
    139.55/208.92 = 90.64/x
  3. Step 3: Cross multiply
    139.55x = 208.92 × 90.64
  4. Step 4: Simplify right side
    139.55x = 18,936.54
  5. Step 5: Solve for x
    x = 18,936.54/139.55
  6. Step 6: Final answer
    x = 135.70

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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.