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Finding the Fourth Proportional to 85.61, 128.41 and 54.35

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Solution

The fourth proportional to 85.61, 128.41 and 54.35 is: 81.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.61 : 128.41 = 54.35 : x
  2. Step 2: Convert to fraction form
    85.61/128.41 = 54.35/x
  3. Step 3: Cross multiply
    85.61x = 128.41 × 54.35
  4. Step 4: Simplify right side
    85.61x = 6,978.31
  5. Step 5: Solve for x
    x = 6,978.31/85.61
  6. Step 6: Final answer
    x = 81.51

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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.