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Finding the Fourth Proportional to 72.12, 99.40 and 55.76

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Solution

The fourth proportional to 72.12, 99.40 and 55.76 is: 76.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.12 : 99.40 = 55.76 : x
  2. Step 2: Convert to fraction form
    72.12/99.40 = 55.76/x
  3. Step 3: Cross multiply
    72.12x = 99.40 × 55.76
  4. Step 4: Simplify right side
    72.12x = 5,542.54
  5. Step 5: Solve for x
    x = 5,542.54/72.12
  6. Step 6: Final answer
    x = 76.85

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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.