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Finding the Fourth Proportional to 428.36, 643.15 and 408.79

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Solution

The fourth proportional to 428.36, 643.15 and 408.79 is: 613.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.36 : 643.15 = 408.79 : x
  2. Step 2: Convert to fraction form
    428.36/643.15 = 408.79/x
  3. Step 3: Cross multiply
    428.36x = 643.15 × 408.79
  4. Step 4: Simplify right side
    428.36x = 262,910.07
  5. Step 5: Solve for x
    x = 262,910.07/428.36
  6. Step 6: Final answer
    x = 613.76

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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.