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Finding the Fourth Proportional to 139.58, 192.34 and 128.78

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Solution

The fourth proportional to 139.58, 192.34 and 128.78 is: 177.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    139.58 : 192.34 = 128.78 : x
  2. Step 2: Convert to fraction form
    139.58/192.34 = 128.78/x
  3. Step 3: Cross multiply
    139.58x = 192.34 × 128.78
  4. Step 4: Simplify right side
    139.58x = 24,769.55
  5. Step 5: Solve for x
    x = 24,769.55/139.58
  6. Step 6: Final answer
    x = 177.46

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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.