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Finding the Fourth Proportional to 311.40, 429.64 and 187.09

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Solution

The fourth proportional to 311.40, 429.64 and 187.09 is: 258.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    311.40 : 429.64 = 187.09 : x
  2. Step 2: Convert to fraction form
    311.40/429.64 = 187.09/x
  3. Step 3: Cross multiply
    311.40x = 429.64 × 187.09
  4. Step 4: Simplify right side
    311.40x = 80,379.81
  5. Step 5: Solve for x
    x = 80,379.81/311.40
  6. Step 6: Final answer
    x = 258.12

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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.