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Finding the Fourth Proportional to 120.75, 180.96 and 77.28

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Solution

The fourth proportional to 120.75, 180.96 and 77.28 is: 115.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    120.75 : 180.96 = 77.28 : x
  2. Step 2: Convert to fraction form
    120.75/180.96 = 77.28/x
  3. Step 3: Cross multiply
    120.75x = 180.96 × 77.28
  4. Step 4: Simplify right side
    120.75x = 13,984.59
  5. Step 5: Solve for x
    x = 13,984.59/120.75
  6. Step 6: Final answer
    x = 115.81

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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.