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Finding the Fourth Proportional to 70.31, 105.47 and 39.86

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Solution

The fourth proportional to 70.31, 105.47 and 39.86 is: 59.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    70.31 : 105.47 = 39.86 : x
  2. Step 2: Convert to fraction form
    70.31/105.47 = 39.86/x
  3. Step 3: Cross multiply
    70.31x = 105.47 × 39.86
  4. Step 4: Simplify right side
    70.31x = 4,203.31
  5. Step 5: Solve for x
    x = 4,203.31/70.31
  6. Step 6: Final answer
    x = 59.79

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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.