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Finding the Fourth Proportional to 78.31, 117.45 and 47.86

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Solution

The fourth proportional to 78.31, 117.45 and 47.86 is: 71.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.31 : 117.45 = 47.86 : x
  2. Step 2: Convert to fraction form
    78.31/117.45 = 47.86/x
  3. Step 3: Cross multiply
    78.31x = 117.45 × 47.86
  4. Step 4: Simplify right side
    78.31x = 5,620.57
  5. Step 5: Solve for x
    x = 5,620.57/78.31
  6. Step 6: Final answer
    x = 71.78

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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.