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Finding the Fourth Proportional to 82.56, 123.78 and 39.21

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Solution

The fourth proportional to 82.56, 123.78 and 39.21 is: 58.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.56 : 123.78 = 39.21 : x
  2. Step 2: Convert to fraction form
    82.56/123.78 = 39.21/x
  3. Step 3: Cross multiply
    82.56x = 123.78 × 39.21
  4. Step 4: Simplify right side
    82.56x = 4,853.41
  5. Step 5: Solve for x
    x = 4,853.41/82.56
  6. Step 6: Final answer
    x = 58.79

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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.