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Finding the Fourth Proportional to 115.31, 172.85 and 54.40

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Solution

The fourth proportional to 115.31, 172.85 and 54.40 is: 81.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.31 : 172.85 = 54.40 : x
  2. Step 2: Convert to fraction form
    115.31/172.85 = 54.40/x
  3. Step 3: Cross multiply
    115.31x = 172.85 × 54.40
  4. Step 4: Simplify right side
    115.31x = 9,401.90
  5. Step 5: Solve for x
    x = 9,401.90/115.31
  6. Step 6: Final answer
    x = 81.54

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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.