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Finding the Fourth Proportional to 80.64, 111.42 and 76.90

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Solution

The fourth proportional to 80.64, 111.42 and 76.90 is: 106.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.64 : 111.42 = 76.90 : x
  2. Step 2: Convert to fraction form
    80.64/111.42 = 76.90/x
  3. Step 3: Cross multiply
    80.64x = 111.42 × 76.90
  4. Step 4: Simplify right side
    80.64x = 8,568.20
  5. Step 5: Solve for x
    x = 8,568.20/80.64
  6. Step 6: Final answer
    x = 106.25

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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.