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Finding the Fourth Proportional to 86.14, 129.16 and 31.28

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Solution

The fourth proportional to 86.14, 129.16 and 31.28 is: 46.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.14 : 129.16 = 31.28 : x
  2. Step 2: Convert to fraction form
    86.14/129.16 = 31.28/x
  3. Step 3: Cross multiply
    86.14x = 129.16 × 31.28
  4. Step 4: Simplify right side
    86.14x = 4,039.40
  5. Step 5: Solve for x
    x = 4,039.40/86.14
  6. Step 6: Final answer
    x = 46.89

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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.