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Finding the Fourth Proportional to 82.56, 123.84 and 31.20

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Solution

The fourth proportional to 82.56, 123.84 and 31.20 is: 46.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.56 : 123.84 = 31.20 : x
  2. Step 2: Convert to fraction form
    82.56/123.84 = 31.20/x
  3. Step 3: Cross multiply
    82.56x = 123.84 × 31.20
  4. Step 4: Simplify right side
    82.56x = 3,863.75
  5. Step 5: Solve for x
    x = 3,863.75/82.56
  6. Step 6: Final answer
    x = 46.80

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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.