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Finding the Fourth Proportional to 72.38, 99.89 and 39.63

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Solution

The fourth proportional to 72.38, 99.89 and 39.63 is: 54.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.38 : 99.89 = 39.63 : x
  2. Step 2: Convert to fraction form
    72.38/99.89 = 39.63/x
  3. Step 3: Cross multiply
    72.38x = 99.89 × 39.63
  4. Step 4: Simplify right side
    72.38x = 3,958.88
  5. Step 5: Solve for x
    x = 3,958.88/72.38
  6. Step 6: Final answer
    x = 54.70

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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.