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Finding the Fourth Proportional to 279.50, 385.90 and 221.72

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Solution

The fourth proportional to 279.50, 385.90 and 221.72 is: 306.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    279.50 : 385.90 = 221.72 : x
  2. Step 2: Convert to fraction form
    279.50/385.90 = 221.72/x
  3. Step 3: Cross multiply
    279.50x = 385.90 × 221.72
  4. Step 4: Simplify right side
    279.50x = 85,559.26
  5. Step 5: Solve for x
    x = 85,559.26/279.50
  6. Step 6: Final answer
    x = 306.12

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.