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Finding the Fourth Proportional to 81.79, 122.60 and 30.40

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Solution

The fourth proportional to 81.79, 122.60 and 30.40 is: 45.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    81.79 : 122.60 = 30.40 : x
  2. Step 2: Convert to fraction form
    81.79/122.60 = 30.40/x
  3. Step 3: Cross multiply
    81.79x = 122.60 × 30.40
  4. Step 4: Simplify right side
    81.79x = 3,726.81
  5. Step 5: Solve for x
    x = 3,726.81/81.79
  6. Step 6: Final answer
    x = 45.57

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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.