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Finding the Fourth Proportional to 428.37, 643.10 and 405.69

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Solution

The fourth proportional to 428.37, 643.10 and 405.69 is: 609.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.37 : 643.10 = 405.69 : x
  2. Step 2: Convert to fraction form
    428.37/643.10 = 405.69/x
  3. Step 3: Cross multiply
    428.37x = 643.10 × 405.69
  4. Step 4: Simplify right side
    428.37x = 260,897.21
  5. Step 5: Solve for x
    x = 260,897.21/428.37
  6. Step 6: Final answer
    x = 609.05

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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.