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Finding the Fourth Proportional to 428.88, 639.92 and 383.78

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Solution

The fourth proportional to 428.88, 639.92 and 383.78 is: 572.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.88 : 639.92 = 383.78 : x
  2. Step 2: Convert to fraction form
    428.88/639.92 = 383.78/x
  3. Step 3: Cross multiply
    428.88x = 639.92 × 383.78
  4. Step 4: Simplify right side
    428.88x = 245,588.50
  5. Step 5: Solve for x
    x = 245,588.50/428.88
  6. Step 6: Final answer
    x = 572.63

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.