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Finding the Fourth Proportional to 427.30, 640.74 and 138.70

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Solution

The fourth proportional to 427.30, 640.74 and 138.70 is: 207.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.30 : 640.74 = 138.70 : x
  2. Step 2: Convert to fraction form
    427.30/640.74 = 138.70/x
  3. Step 3: Cross multiply
    427.30x = 640.74 × 138.70
  4. Step 4: Simplify right side
    427.30x = 88,870.64
  5. Step 5: Solve for x
    x = 88,870.64/427.30
  6. Step 6: Final answer
    x = 207.98

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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.