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Finding the Fourth Proportional to 85.12, 128.32 and 69.28

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Solution

The fourth proportional to 85.12, 128.32 and 69.28 is: 104.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.12 : 128.32 = 69.28 : x
  2. Step 2: Convert to fraction form
    85.12/128.32 = 69.28/x
  3. Step 3: Cross multiply
    85.12x = 128.32 × 69.28
  4. Step 4: Simplify right side
    85.12x = 8,890.01
  5. Step 5: Solve for x
    x = 8,890.01/85.12
  6. Step 6: Final answer
    x = 104.44

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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.