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Finding the Fourth Proportional to 139.85, 192.90 and 90.71

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Solution

The fourth proportional to 139.85, 192.90 and 90.71 is: 125.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.85 : 192.90 = 90.71 : x
  2. Step 2: Convert to fraction form
    139.85/192.90 = 90.71/x
  3. Step 3: Cross multiply
    139.85x = 192.90 × 90.71
  4. Step 4: Simplify right side
    139.85x = 17,497.99
  5. Step 5: Solve for x
    x = 17,497.99/139.85
  6. Step 6: Final answer
    x = 125.12

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.