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Finding the Fourth Proportional to 139.40, 208.96 and 90.68

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Solution

The fourth proportional to 139.40, 208.96 and 90.68 is: 135.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.40 : 208.96 = 90.68 : x
  2. Step 2: Convert to fraction form
    139.40/208.96 = 90.68/x
  3. Step 3: Cross multiply
    139.40x = 208.96 × 90.68
  4. Step 4: Simplify right side
    139.40x = 18,948.04
  5. Step 5: Solve for x
    x = 18,948.04/139.40
  6. Step 6: Final answer
    x = 135.93

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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.