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Finding the Fourth Proportional to 231.78, 319.80 and 128.28

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Solution

The fourth proportional to 231.78, 319.80 and 128.28 is: 177.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    231.78 : 319.80 = 128.28 : x
  2. Step 2: Convert to fraction form
    231.78/319.80 = 128.28/x
  3. Step 3: Cross multiply
    231.78x = 319.80 × 128.28
  4. Step 4: Simplify right side
    231.78x = 41,023.94
  5. Step 5: Solve for x
    x = 41,023.94/231.78
  6. Step 6: Final answer
    x = 177.00

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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.