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Finding the Fourth Proportional to 81.89, 122.75 and 56.15

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Solution

The fourth proportional to 81.89, 122.75 and 56.15 is: 84.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.89 : 122.75 = 56.15 : x
  2. Step 2: Convert to fraction form
    81.89/122.75 = 56.15/x
  3. Step 3: Cross multiply
    81.89x = 122.75 × 56.15
  4. Step 4: Simplify right side
    81.89x = 6,892.13
  5. Step 5: Solve for x
    x = 6,892.13/81.89
  6. Step 6: Final answer
    x = 84.16

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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.