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Finding the Fourth Proportional to 81.40, 122 and 55.68

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Solution

The fourth proportional to 81.40, 122 and 55.68 is: 83.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.40 : 122 = 55.68 : x
  2. Step 2: Convert to fraction form
    81.40/122 = 55.68/x
  3. Step 3: Cross multiply
    81.40x = 122 × 55.68
  4. Step 4: Simplify right side
    81.40x = 6,792.96
  5. Step 5: Solve for x
    x = 6,792.96/81.40
  6. Step 6: Final answer
    x = 83.45

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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.