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Finding the Fourth Proportional to 86.38, 129.42 and 56

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Solution

The fourth proportional to 86.38, 129.42 and 56 is: 83.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.38 : 129.42 = 56 : x
  2. Step 2: Convert to fraction form
    86.38/129.42 = 56/x
  3. Step 3: Cross multiply
    86.38x = 129.42 × 56
  4. Step 4: Simplify right side
    86.38x = 7,247.52
  5. Step 5: Solve for x
    x = 7,247.52/86.38
  6. Step 6: Final answer
    x = 83.90

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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.