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Finding the Fourth Proportional to 115.12, 172.55 and 80.70

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Solution

The fourth proportional to 115.12, 172.55 and 80.70 is: 120.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.12 : 172.55 = 80.70 : x
  2. Step 2: Convert to fraction form
    115.12/172.55 = 80.70/x
  3. Step 3: Cross multiply
    115.12x = 172.55 × 80.70
  4. Step 4: Simplify right side
    115.12x = 13,923.89
  5. Step 5: Solve for x
    x = 13,923.89/115.12
  6. Step 6: Final answer
    x = 120.95

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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.