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Finding the Fourth Proportional to 115.25, 172.80 and 80.55

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Solution

The fourth proportional to 115.25, 172.80 and 80.55 is: 120.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.25 : 172.80 = 80.55 : x
  2. Step 2: Convert to fraction form
    115.25/172.80 = 80.55/x
  3. Step 3: Cross multiply
    115.25x = 172.80 × 80.55
  4. Step 4: Simplify right side
    115.25x = 13,919.04
  5. Step 5: Solve for x
    x = 13,919.04/115.25
  6. Step 6: Final answer
    x = 120.78

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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.