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Finding the Fourth Proportional to 85.52, 128.27 and 21.39

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Solution

The fourth proportional to 85.52, 128.27 and 21.39 is: 32.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.52 : 128.27 = 21.39 : x
  2. Step 2: Convert to fraction form
    85.52/128.27 = 21.39/x
  3. Step 3: Cross multiply
    85.52x = 128.27 × 21.39
  4. Step 4: Simplify right side
    85.52x = 2,743.70
  5. Step 5: Solve for x
    x = 2,743.70/85.52
  6. Step 6: Final answer
    x = 32.08

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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.