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Finding the Fourth Proportional to 428.68, 643.20 and 291.88

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Solution

The fourth proportional to 428.68, 643.20 and 291.88 is: 437.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.68 : 643.20 = 291.88 : x
  2. Step 2: Convert to fraction form
    428.68/643.20 = 291.88/x
  3. Step 3: Cross multiply
    428.68x = 643.20 × 291.88
  4. Step 4: Simplify right side
    428.68x = 187,737.22
  5. Step 5: Solve for x
    x = 187,737.22/428.68
  6. Step 6: Final answer
    x = 437.94

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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.