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Finding the Fourth Proportional to 82.12, 123.20 and 30.78

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Solution

The fourth proportional to 82.12, 123.20 and 30.78 is: 46.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.12 : 123.20 = 30.78 : x
  2. Step 2: Convert to fraction form
    82.12/123.20 = 30.78/x
  3. Step 3: Cross multiply
    82.12x = 123.20 × 30.78
  4. Step 4: Simplify right side
    82.12x = 3,792.10
  5. Step 5: Solve for x
    x = 3,792.10/82.12
  6. Step 6: Final answer
    x = 46.18

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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.