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Finding the Fourth Proportional to 85.34, 128.05 and 31.24

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Solution

The fourth proportional to 85.34, 128.05 and 31.24 is: 46.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.34 : 128.05 = 31.24 : x
  2. Step 2: Convert to fraction form
    85.34/128.05 = 31.24/x
  3. Step 3: Cross multiply
    85.34x = 128.05 × 31.24
  4. Step 4: Simplify right side
    85.34x = 4,000.13
  5. Step 5: Solve for x
    x = 4,000.13/85.34
  6. Step 6: Final answer
    x = 46.87

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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.