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Finding the Fourth Proportional to 390.99, 539.60 and 225.20

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Solution

The fourth proportional to 390.99, 539.60 and 225.20 is: 310.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.99 : 539.60 = 225.20 : x
  2. Step 2: Convert to fraction form
    390.99/539.60 = 225.20/x
  3. Step 3: Cross multiply
    390.99x = 539.60 × 225.20
  4. Step 4: Simplify right side
    390.99x = 121,516.79
  5. Step 5: Solve for x
    x = 121,516.79/390.99
  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.