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Finding the Fourth Proportional to 279.78, 420.21 and 171.78

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Solution

The fourth proportional to 279.78, 420.21 and 171.78 is: 258.00

Step by Step Solution

  1. Step 1: Write the proportion equation
    279.78 : 420.21 = 171.78 : x
  2. Step 2: Convert to fraction form
    279.78/420.21 = 171.78/x
  3. Step 3: Cross multiply
    279.78x = 420.21 × 171.78
  4. Step 4: Simplify right side
    279.78x = 72,183.67
  5. Step 5: Solve for x
    x = 72,183.67/279.78
  6. Step 6: Final answer
    x = 258.00

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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.