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Finding the Fourth Proportional to 85.66, 128.28 and 76.65

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Solution

The fourth proportional to 85.66, 128.28 and 76.65 is: 114.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.66 : 128.28 = 76.65 : x
  2. Step 2: Convert to fraction form
    85.66/128.28 = 76.65/x
  3. Step 3: Cross multiply
    85.66x = 128.28 × 76.65
  4. Step 4: Simplify right side
    85.66x = 9,832.47
  5. Step 5: Solve for x
    x = 9,832.47/85.66
  6. Step 6: Final answer
    x = 114.79

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.