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Finding the Fourth Proportional to 831.20, 1,245.30 and 397.40

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Solution

The fourth proportional to 831.20, 1,245.30 and 397.40 is: 595.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    831.20 : 1,245.30 = 397.40 : x
  2. Step 2: Convert to fraction form
    831.20/1,245.30 = 397.40/x
  3. Step 3: Cross multiply
    831.20x = 1,245.30 × 397.40
  4. Step 4: Simplify right side
    831.20x = 494,882.22
  5. Step 5: Solve for x
    x = 494,882.22/831.20
  6. Step 6: Final answer
    x = 595.38

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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.