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Finding the Fourth Proportional to 82.21, 123.54 and 76.86

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Solution

The fourth proportional to 82.21, 123.54 and 76.86 is: 115.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    82.21 : 123.54 = 76.86 : x
  2. Step 2: Convert to fraction form
    82.21/123.54 = 76.86/x
  3. Step 3: Cross multiply
    82.21x = 123.54 × 76.86
  4. Step 4: Simplify right side
    82.21x = 9,495.28
  5. Step 5: Solve for x
    x = 9,495.28/82.21
  6. Step 6: Final answer
    x = 115.50

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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.