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Finding the Fourth Proportional to 85.52, 128.59 and 55.15

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Solution

The fourth proportional to 85.52, 128.59 and 55.15 is: 82.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.52 : 128.59 = 55.15 : x
  2. Step 2: Convert to fraction form
    85.52/128.59 = 55.15/x
  3. Step 3: Cross multiply
    85.52x = 128.59 × 55.15
  4. Step 4: Simplify right side
    85.52x = 7,091.28
  5. Step 5: Solve for x
    x = 7,091.28/85.52
  6. Step 6: Final answer
    x = 82.92

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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.