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Finding the Fourth Proportional to 85.38, 128.03 and 42.11

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Solution

The fourth proportional to 85.38, 128.03 and 42.11 is: 63.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.38 : 128.03 = 42.11 : x
  2. Step 2: Convert to fraction form
    85.38/128.03 = 42.11/x
  3. Step 3: Cross multiply
    85.38x = 128.03 × 42.11
  4. Step 4: Simplify right side
    85.38x = 5,391.34
  5. Step 5: Solve for x
    x = 5,391.34/85.38
  6. Step 6: Final answer
    x = 63.15

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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.