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Finding the Fourth Proportional to 139.62, 208.37 and 128.79

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Solution

The fourth proportional to 139.62, 208.37 and 128.79 is: 192.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.62 : 208.37 = 128.79 : x
  2. Step 2: Convert to fraction form
    139.62/208.37 = 128.79/x
  3. Step 3: Cross multiply
    139.62x = 208.37 × 128.79
  4. Step 4: Simplify right side
    139.62x = 26,836.29
  5. Step 5: Solve for x
    x = 26,836.29/139.62
  6. Step 6: Final answer
    x = 192.20

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.