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Finding the Fourth Proportional to 421.34, 629.69 and 311.90

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Solution

The fourth proportional to 421.34, 629.69 and 311.90 is: 466.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.34 : 629.69 = 311.90 : x
  2. Step 2: Convert to fraction form
    421.34/629.69 = 311.90/x
  3. Step 3: Cross multiply
    421.34x = 629.69 × 311.90
  4. Step 4: Simplify right side
    421.34x = 196,395.60
  5. Step 5: Solve for x
    x = 196,395.60/421.34
  6. Step 6: Final answer
    x = 466.13

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.