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Finding the Fourth Proportional to 311.13, 429.21 and 186.78

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Solution

The fourth proportional to 311.13, 429.21 and 186.78 is: 257.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.13 : 429.21 = 186.78 : x
  2. Step 2: Convert to fraction form
    311.13/429.21 = 186.78/x
  3. Step 3: Cross multiply
    311.13x = 429.21 × 186.78
  4. Step 4: Simplify right side
    311.13x = 80,167.84
  5. Step 5: Solve for x
    x = 80,167.84/311.13
  6. Step 6: Final answer
    x = 257.67

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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.