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Finding the Fourth Proportional to 426.37, 639.90 and 221

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Solution

The fourth proportional to 426.37, 639.90 and 221 is: 331.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.37 : 639.90 = 221 : x
  2. Step 2: Convert to fraction form
    426.37/639.90 = 221/x
  3. Step 3: Cross multiply
    426.37x = 639.90 × 221
  4. Step 4: Simplify right side
    426.37x = 141,417.90
  5. Step 5: Solve for x
    x = 141,417.90/426.37
  6. Step 6: Final answer
    x = 331.68

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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.