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Finding the Fourth Proportional to 428.45, 643.07 and 311.43

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Solution

The fourth proportional to 428.45, 643.07 and 311.43 is: 467.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.45 : 643.07 = 311.43 : x
  2. Step 2: Convert to fraction form
    428.45/643.07 = 311.43/x
  3. Step 3: Cross multiply
    428.45x = 643.07 × 311.43
  4. Step 4: Simplify right side
    428.45x = 200,274.48
  5. Step 5: Solve for x
    x = 200,274.48/428.45
  6. Step 6: Final answer
    x = 467.45

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.