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Finding the Fourth Proportional to 428.79, 644.42 and 285.42

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Solution

The fourth proportional to 428.79, 644.42 and 285.42 is: 428.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.79 : 644.42 = 285.42 : x
  2. Step 2: Convert to fraction form
    428.79/644.42 = 285.42/x
  3. Step 3: Cross multiply
    428.79x = 644.42 × 285.42
  4. Step 4: Simplify right side
    428.79x = 183,928.93
  5. Step 5: Solve for x
    x = 183,928.93/428.79
  6. Step 6: Final answer
    x = 428.95

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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.