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Finding the Fourth Proportional to 82.57, 123.79 and 31.20

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Solution

The fourth proportional to 82.57, 123.79 and 31.20 is: 46.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.57 : 123.79 = 31.20 : x
  2. Step 2: Convert to fraction form
    82.57/123.79 = 31.20/x
  3. Step 3: Cross multiply
    82.57x = 123.79 × 31.20
  4. Step 4: Simplify right side
    82.57x = 3,862.25
  5. Step 5: Solve for x
    x = 3,862.25/82.57
  6. Step 6: Final answer
    x = 46.78

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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.