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Finding the Fourth Proportional to 85.06, 128.04 and 80.64

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Solution

The fourth proportional to 85.06, 128.04 and 80.64 is: 121.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.06 : 128.04 = 80.64 : x
  2. Step 2: Convert to fraction form
    85.06/128.04 = 80.64/x
  3. Step 3: Cross multiply
    85.06x = 128.04 × 80.64
  4. Step 4: Simplify right side
    85.06x = 10,325.15
  5. Step 5: Solve for x
    x = 10,325.15/85.06
  6. Step 6: Final answer
    x = 121.39

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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.