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Finding the Fourth Proportional to 128.12, 176.74 and 81.44

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Solution

The fourth proportional to 128.12, 176.74 and 81.44 is: 112.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.12 : 176.74 = 81.44 : x
  2. Step 2: Convert to fraction form
    128.12/176.74 = 81.44/x
  3. Step 3: Cross multiply
    128.12x = 176.74 × 81.44
  4. Step 4: Simplify right side
    128.12x = 14,393.71
  5. Step 5: Solve for x
    x = 14,393.71/128.12
  6. Step 6: Final answer
    x = 112.35

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.