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Finding the Fourth Proportional to 128.36, 177.13 and 83.42

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Solution

The fourth proportional to 128.36, 177.13 and 83.42 is: 115.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.36 : 177.13 = 83.42 : x
  2. Step 2: Convert to fraction form
    128.36/177.13 = 83.42/x
  3. Step 3: Cross multiply
    128.36x = 177.13 × 83.42
  4. Step 4: Simplify right side
    128.36x = 14,776.18
  5. Step 5: Solve for x
    x = 14,776.18/128.36
  6. Step 6: Final answer
    x = 115.12

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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.