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Finding the Fourth Proportional to 81.68, 122.15 and 47.35

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Solution

The fourth proportional to 81.68, 122.15 and 47.35 is: 70.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.68 : 122.15 = 47.35 : x
  2. Step 2: Convert to fraction form
    81.68/122.15 = 47.35/x
  3. Step 3: Cross multiply
    81.68x = 122.15 × 47.35
  4. Step 4: Simplify right side
    81.68x = 5,783.62
  5. Step 5: Solve for x
    x = 5,783.62/81.68
  6. Step 6: Final answer
    x = 70.81

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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.