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Finding the Fourth Proportional to 291.72, 402.40 and 221.81

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Solution

The fourth proportional to 291.72, 402.40 and 221.81 is: 305.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    291.72 : 402.40 = 221.81 : x
  2. Step 2: Convert to fraction form
    291.72/402.40 = 221.81/x
  3. Step 3: Cross multiply
    291.72x = 402.40 × 221.81
  4. Step 4: Simplify right side
    291.72x = 89,253.78
  5. Step 5: Solve for x
    x = 89,253.78/291.72
  6. Step 6: Final answer
    x = 305.96

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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.