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Finding the Fourth Proportional to 128.84, 193.20 and 74.72

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Solution

The fourth proportional to 128.84, 193.20 and 74.72 is: 112.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.84 : 193.20 = 74.72 : x
  2. Step 2: Convert to fraction form
    128.84/193.20 = 74.72/x
  3. Step 3: Cross multiply
    128.84x = 193.20 × 74.72
  4. Step 4: Simplify right side
    128.84x = 14,435.90
  5. Step 5: Solve for x
    x = 14,435.90/128.84
  6. Step 6: Final answer
    x = 112.05

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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.