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Finding the Fourth Proportional to 76.64, 115.42 and 69.12

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Solution

The fourth proportional to 76.64, 115.42 and 69.12 is: 104.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.64 : 115.42 = 69.12 : x
  2. Step 2: Convert to fraction form
    76.64/115.42 = 69.12/x
  3. Step 3: Cross multiply
    76.64x = 115.42 × 69.12
  4. Step 4: Simplify right side
    76.64x = 7,977.83
  5. Step 5: Solve for x
    x = 7,977.83/76.64
  6. Step 6: Final answer
    x = 104.09

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.