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Finding the Fourth Proportional to 81.44, 122.30 and 78

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Solution

The fourth proportional to 81.44, 122.30 and 78 is: 117.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.44 : 122.30 = 78 : x
  2. Step 2: Convert to fraction form
    81.44/122.30 = 78/x
  3. Step 3: Cross multiply
    81.44x = 122.30 × 78
  4. Step 4: Simplify right side
    81.44x = 9,539.40
  5. Step 5: Solve for x
    x = 9,539.40/81.44
  6. Step 6: Final answer
    x = 117.13

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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.