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Finding the Fourth Proportional to 428.68, 638.90 and 425.11

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Solution

The fourth proportional to 428.68, 638.90 and 425.11 is: 633.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.68 : 638.90 = 425.11 : x
  2. Step 2: Convert to fraction form
    428.68/638.90 = 425.11/x
  3. Step 3: Cross multiply
    428.68x = 638.90 × 425.11
  4. Step 4: Simplify right side
    428.68x = 271,597.46
  5. Step 5: Solve for x
    x = 271,597.46/428.68
  6. Step 6: Final answer
    x = 633.57

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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.