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Finding the Fourth Proportional to 421.40, 581.11 and 311.11

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Solution

The fourth proportional to 421.40, 581.11 and 311.11 is: 429.01

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.40 : 581.11 = 311.11 : x
  2. Step 2: Convert to fraction form
    421.40/581.11 = 311.11/x
  3. Step 3: Cross multiply
    421.40x = 581.11 × 311.11
  4. Step 4: Simplify right side
    421.40x = 180,786.90
  5. Step 5: Solve for x
    x = 180,786.90/421.40
  6. Step 6: Final answer
    x = 429.01

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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.