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Finding the Fourth Proportional to 139.32, 191.28 and 128.40

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Solution

The fourth proportional to 139.32, 191.28 and 128.40 is: 176.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.32 : 191.28 = 128.40 : x
  2. Step 2: Convert to fraction form
    139.32/191.28 = 128.40/x
  3. Step 3: Cross multiply
    139.32x = 191.28 × 128.40
  4. Step 4: Simplify right side
    139.32x = 24,560.35
  5. Step 5: Solve for x
    x = 24,560.35/139.32
  6. Step 6: Final answer
    x = 176.29

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.