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Finding the Fourth Proportional to 278.21, 417.31 and 72.78

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Solution

The fourth proportional to 278.21, 417.31 and 72.78 is: 109.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.21 : 417.31 = 72.78 : x
  2. Step 2: Convert to fraction form
    278.21/417.31 = 72.78/x
  3. Step 3: Cross multiply
    278.21x = 417.31 × 72.78
  4. Step 4: Simplify right side
    278.21x = 30,371.82
  5. Step 5: Solve for x
    x = 30,371.82/278.21
  6. Step 6: Final answer
    x = 109.17

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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.