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Finding the Fourth Proportional to 85.38, 128.02 and 31.25

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Solution

The fourth proportional to 85.38, 128.02 and 31.25 is: 46.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.38 : 128.02 = 31.25 : x
  2. Step 2: Convert to fraction form
    85.38/128.02 = 31.25/x
  3. Step 3: Cross multiply
    85.38x = 128.02 × 31.25
  4. Step 4: Simplify right side
    85.38x = 4,000.63
  5. Step 5: Solve for x
    x = 4,000.63/85.38
  6. Step 6: Final answer
    x = 46.86

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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.