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Finding the Fourth Proportional to 128.02, 176.70 and 81.42

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Solution

The fourth proportional to 128.02, 176.70 and 81.42 is: 112.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.02 : 176.70 = 81.42 : x
  2. Step 2: Convert to fraction form
    128.02/176.70 = 81.42/x
  3. Step 3: Cross multiply
    128.02x = 176.70 × 81.42
  4. Step 4: Simplify right side
    128.02x = 14,386.91
  5. Step 5: Solve for x
    x = 14,386.91/128.02
  6. Step 6: Final answer
    x = 112.38

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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.