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Finding the Fourth Proportional to 42.72, 58.89 and 31.78

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Solution

The fourth proportional to 42.72, 58.89 and 31.78 is: 43.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    42.72 : 58.89 = 31.78 : x
  2. Step 2: Convert to fraction form
    42.72/58.89 = 31.78/x
  3. Step 3: Cross multiply
    42.72x = 58.89 × 31.78
  4. Step 4: Simplify right side
    42.72x = 1,871.52
  5. Step 5: Solve for x
    x = 1,871.52/42.72
  6. Step 6: Final answer
    x = 43.81

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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.