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Finding the Fourth Proportional to 128.12, 192.18 and 74

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Solution

The fourth proportional to 128.12, 192.18 and 74 is: 111

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.12 : 192.18 = 74 : x
  2. Step 2: Convert to fraction form
    128.12/192.18 = 74/x
  3. Step 3: Cross multiply
    128.12x = 192.18 × 74
  4. Step 4: Simplify right side
    128.12x = 14,221.32
  5. Step 5: Solve for x
    x = 14,221.32/128.12
  6. Step 6: Final answer
    x = 111

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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.