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Finding the Fourth Proportional to 82, 113.28 and 72.80

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Solution

The fourth proportional to 82, 113.28 and 72.80 is: 100.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    82 : 113.28 = 72.80 : x
  2. Step 2: Convert to fraction form
    82/113.28 = 72.80/x
  3. Step 3: Cross multiply
    82x = 113.28 × 72.80
  4. Step 4: Simplify right side
    82x = 8,246.78
  5. Step 5: Solve for x
    x = 8,246.78/82
  6. Step 6: Final answer
    x = 100.57

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.