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Finding the Fourth Proportional to 390.42, 584.85 and 216.81

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Solution

The fourth proportional to 390.42, 584.85 and 216.81 is: 324.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.42 : 584.85 = 216.81 : x
  2. Step 2: Convert to fraction form
    390.42/584.85 = 216.81/x
  3. Step 3: Cross multiply
    390.42x = 584.85 × 216.81
  4. Step 4: Simplify right side
    390.42x = 126,802.14
  5. Step 5: Solve for x
    x = 126,802.14/390.42
  6. Step 6: Final answer
    x = 324.78

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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.