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Finding the Fourth Proportional to 427.50, 639.86 and 221.78

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Solution

The fourth proportional to 427.50, 639.86 and 221.78 is: 331.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    427.50 : 639.86 = 221.78 : x
  2. Step 2: Convert to fraction form
    427.50/639.86 = 221.78/x
  3. Step 3: Cross multiply
    427.50x = 639.86 × 221.78
  4. Step 4: Simplify right side
    427.50x = 141,905.51
  5. Step 5: Solve for x
    x = 141,905.51/427.50
  6. Step 6: Final answer
    x = 331.94

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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.