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Finding the Fourth Proportional to 139.07, 207.38 and 128.81

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Solution

The fourth proportional to 139.07, 207.38 and 128.81 is: 192.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.07 : 207.38 = 128.81 : x
  2. Step 2: Convert to fraction form
    139.07/207.38 = 128.81/x
  3. Step 3: Cross multiply
    139.07x = 207.38 × 128.81
  4. Step 4: Simplify right side
    139.07x = 26,710.94
  5. Step 5: Solve for x
    x = 26,710.94/139.07
  6. Step 6: Final answer
    x = 192.08

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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.