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Finding the Fourth Proportional to 428.76, 639.90 and 425.93

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Solution

The fourth proportional to 428.76, 639.90 and 425.93 is: 635.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    428.76 : 639.90 = 425.93 : x
  2. Step 2: Convert to fraction form
    428.76/639.90 = 425.93/x
  3. Step 3: Cross multiply
    428.76x = 639.90 × 425.93
  4. Step 4: Simplify right side
    428.76x = 272,549.41
  5. Step 5: Solve for x
    x = 272,549.41/428.76
  6. Step 6: Final answer
    x = 635.67

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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.