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Finding the Fourth Proportional to 390.99, 539.56 and 225.21

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Solution

The fourth proportional to 390.99, 539.56 and 225.21 is: 310.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.99 : 539.56 = 225.21 : x
  2. Step 2: Convert to fraction form
    390.99/539.56 = 225.21/x
  3. Step 3: Cross multiply
    390.99x = 539.56 × 225.21
  4. Step 4: Simplify right side
    390.99x = 121,516.61
  5. Step 5: Solve for x
    x = 121,516.61/390.99
  6. Step 6: Final answer
    x = 310.79

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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.