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Finding the Fourth Proportional to 85.34, 128.02 and 31.22

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Solution

The fourth proportional to 85.34, 128.02 and 31.22 is: 46.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.34 : 128.02 = 31.22 : x
  2. Step 2: Convert to fraction form
    85.34/128.02 = 31.22/x
  3. Step 3: Cross multiply
    85.34x = 128.02 × 31.22
  4. Step 4: Simplify right side
    85.34x = 3,996.78
  5. Step 5: Solve for x
    x = 3,996.78/85.34
  6. Step 6: Final answer
    x = 46.83

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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.