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Finding the Fourth Proportional to 390.42, 582.15 and 385.64

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Solution

The fourth proportional to 390.42, 582.15 and 385.64 is: 575.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.42 : 582.15 = 385.64 : x
  2. Step 2: Convert to fraction form
    390.42/582.15 = 385.64/x
  3. Step 3: Cross multiply
    390.42x = 582.15 × 385.64
  4. Step 4: Simplify right side
    390.42x = 224,497.78
  5. Step 5: Solve for x
    x = 224,497.78/390.42
  6. Step 6: Final answer
    x = 575.02

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.