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Finding the Fourth Proportional to 390.89, 539.20 and 258.12

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Solution

The fourth proportional to 390.89, 539.20 and 258.12 is: 356.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.89 : 539.20 = 258.12 : x
  2. Step 2: Convert to fraction form
    390.89/539.20 = 258.12/x
  3. Step 3: Cross multiply
    390.89x = 539.20 × 258.12
  4. Step 4: Simplify right side
    390.89x = 139,174.96
  5. Step 5: Solve for x
    x = 139,174.96/390.89
  6. Step 6: Final answer
    x = 356.04

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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.