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Finding the Fourth Proportional to 231, 318.78 and 139

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Solution

The fourth proportional to 231, 318.78 and 139 is: 191.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    231 : 318.78 = 139 : x
  2. Step 2: Convert to fraction form
    231/318.78 = 139/x
  3. Step 3: Cross multiply
    231x = 318.78 × 139
  4. Step 4: Simplify right side
    231x = 44,310.42
  5. Step 5: Solve for x
    x = 44,310.42/231
  6. Step 6: Final answer
    x = 191.82

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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.