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Finding the Fourth Proportional to 428.40, 639.15 and 382.23

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Solution

The fourth proportional to 428.40, 639.15 and 382.23 is: 570.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.40 : 639.15 = 382.23 : x
  2. Step 2: Convert to fraction form
    428.40/639.15 = 382.23/x
  3. Step 3: Cross multiply
    428.40x = 639.15 × 382.23
  4. Step 4: Simplify right side
    428.40x = 244,302.30
  5. Step 5: Solve for x
    x = 244,302.30/428.40
  6. Step 6: Final answer
    x = 570.27

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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.