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Finding the Fourth Proportional to 139.79, 209.67 and 86.02

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Solution

The fourth proportional to 139.79, 209.67 and 86.02 is: 129.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.79 : 209.67 = 86.02 : x
  2. Step 2: Convert to fraction form
    139.79/209.67 = 86.02/x
  3. Step 3: Cross multiply
    139.79x = 209.67 × 86.02
  4. Step 4: Simplify right side
    139.79x = 18,035.81
  5. Step 5: Solve for x
    x = 18,035.81/139.79
  6. Step 6: Final answer
    x = 129.02

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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.