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Finding the Fourth Proportional to 128.06, 176.65 and 78.85

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Solution

The fourth proportional to 128.06, 176.65 and 78.85 is: 108.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.06 : 176.65 = 78.85 : x
  2. Step 2: Convert to fraction form
    128.06/176.65 = 78.85/x
  3. Step 3: Cross multiply
    128.06x = 176.65 × 78.85
  4. Step 4: Simplify right side
    128.06x = 13,928.85
  5. Step 5: Solve for x
    x = 13,928.85/128.06
  6. Step 6: Final answer
    x = 108.77

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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.