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Finding the Fourth Proportional to 231.72, 319.78 and 128.22

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Solution

The fourth proportional to 231.72, 319.78 and 128.22 is: 176.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    231.72 : 319.78 = 128.22 : x
  2. Step 2: Convert to fraction form
    231.72/319.78 = 128.22/x
  3. Step 3: Cross multiply
    231.72x = 319.78 × 128.22
  4. Step 4: Simplify right side
    231.72x = 41,002.19
  5. Step 5: Solve for x
    x = 41,002.19/231.72
  6. Step 6: Final answer
    x = 176.95

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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.