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Finding the Fourth Proportional to 115.12, 172.64 and 74.78

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Solution

The fourth proportional to 115.12, 172.64 and 74.78 is: 112.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    115.12 : 172.64 = 74.78 : x
  2. Step 2: Convert to fraction form
    115.12/172.64 = 74.78/x
  3. Step 3: Cross multiply
    115.12x = 172.64 × 74.78
  4. Step 4: Simplify right side
    115.12x = 12,910.02
  5. Step 5: Solve for x
    x = 12,910.02/115.12
  6. Step 6: Final answer
    x = 112.14

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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.