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Finding the Fourth Proportional to 82.10, 122.42 and 81.30

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Solution

The fourth proportional to 82.10, 122.42 and 81.30 is: 121.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.10 : 122.42 = 81.30 : x
  2. Step 2: Convert to fraction form
    82.10/122.42 = 81.30/x
  3. Step 3: Cross multiply
    82.10x = 122.42 × 81.30
  4. Step 4: Simplify right side
    82.10x = 9,952.75
  5. Step 5: Solve for x
    x = 9,952.75/82.10
  6. Step 6: Final answer
    x = 121.23

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.