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Finding the Fourth Proportional to 120.40, 180.43 and 81.79

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Solution

The fourth proportional to 120.40, 180.43 and 81.79 is: 122.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.40 : 180.43 = 81.79 : x
  2. Step 2: Convert to fraction form
    120.40/180.43 = 81.79/x
  3. Step 3: Cross multiply
    120.40x = 180.43 × 81.79
  4. Step 4: Simplify right side
    120.40x = 14,756.71
  5. Step 5: Solve for x
    x = 14,756.71/120.40
  6. Step 6: Final answer
    x = 122.57

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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.